Potatoes Au Gratin with Poblanos

Decadence takes center stage with these creamy, crispy, savory, and herbaceous Potatoes au Gratin with Poblanos that will have you diving in for seconds. The holiday classic stays true to traditional flavors while getting a boost of smoky and earthy flavor from roasted poblano peppers.

This is my go-to side for the holidays and most requested potato recipe for family events. It gives you everything you love about a traditional potatoes au gratin recipe with the lemony pop of thyme, garlic laced cream sauce, and nutty bronzed Parmigiano-Reggiano top, but with the addition of grilled poblano peppers.

Potatoes and poblanos are a common pairing in Mexican cuisine and work together in this French dish to add unexpected flavor and texture. Pair this with your Thanksgiving turkey, Christmas prime rib, of even just Sunday habanero mojo chicken.

Why You’ll Love This Recipe

• Easy Process – Unlike many recipes for scalloped potatoes, there is no making a béchamel sauce for this potato recipe. The combination of heavy cream and the starch in the potatoes creates the thick, luscious sauce that hugs the potatoes.
• Make Ahead – I like to call these make ahead potatoes au gratin because they can easily be assembled in advance. When the holidays roll around it’s great to have recipes that you can prep ahead of time so you’re not in a rush to do everything all at once. Because the potatoes are partially cooked in the heavy cream, you can make this a day or two in advance and then bake it off just before serving. Not only do you not have to worry about raw potatoes turning brown, but it also cuts down on the bake time. Pop these into the oven while your main course is resting.
• Balance of Flavors – This delivers the richness you crave in au gratin potatoes, but also has bold pops of flavor that balance the luxurious ingredients like Dijon mustard and steak seasoning.
• Minimal Ingredients – Potatoes, cream, onions, poblanos, there’s nothing complicated about any of the ingredients in this au gratin recipe. You can even swap out the cheese used for your favorite and what you have on hand.

Ingredients

• Potatoes – Yukon gold potatoes hold up well to this scalloped potatoes au gratin recipe without falling apart. They have a firmer flesh than russet potatoes and a thin skin that doesn’t require peeling. They also have a good starch content to help the sauce thicken and develop.
• Aromatics – A sweet onion and garlic add savory flavor and texture to every bite.
• Sauce – Does anything bad ever start with heavy cream? Combined with the starch in the potatoes, the heavy cream naturally thickens as it cooks. Dijon mustard adds tang, bay leaves give that all day cooked flavor, and salt, pepper, and steak seasoning flavor the sauce and potatoes.
• Cheese – We’re keeping it classic with Gruyère cheese going between the layers of potatoes and Parmigiano-Reggiano dusting the top of the casserole begging to be bronzed on the grill or in the oven.
• Poblanos – These earthy and rich peppers add a smoky element once they’re roasted. They give a ton of flavor without adding any heat making this a dish the entire family can enjoy.

How to Make Potatoes au Gratin with Poblanos

• Roast the poblano peppers and chop them. Prepare your grill for direct grilling. If using a gas grill heat it to 400 degrees. Place the poblanos on the hot grate. Roate them ever 1-2 minutes until all sides are charred. Place them into a plastic bag or plastic container and allow them to cool off and steam. Once cooled, brush off the charred skin and remove the stem and seeds. Slice the poblanos into thin strips.
• Slice your potatoes and grate the cheese. Use a mandoline to thinly slice the potatoes. Grate the cheeses.
• Saute your aromatics. Heat a large skillet over medium heat and add the butter, allowing it to melt. Add the sweet onion slices and allow them to cook, stirring occasionally, until they’re translucent, 4-6 minutes. Add the garlic and cook for another minute until fragrant.

• Simmer the potatoes. Add the potato slices, thyme, bay leaves, heavy cream, and spices. Stir to combine making sure the potatoes are all coated in the cream. Allow the cream to come to a simmer. Let the potatoes cook in the cream mixture until they’re fork tender and the cream has thickened. Make sure to occasionally stir so they cook evenly. It should take 10-15 minutes. Remove the bay leaves and thyme sprigs and stir in the Dijon. Taste and adjust seasoning if needed.
• Assemble your casserole. Preheat the oven or grill to 375 degrees. Butter a gratin dish or cast iron skillet. Pour half of the potato mixture into the dish. Sprinkle the Gruyère cheese over the top. Pour the remaining potato mixture over the top. Add the parmesan cheese over the top of the potatoes. Sprinkle extra thyme leaves and freshly cracked black pepper over the top.
• Bake off the potatoes au gratin. If making these on the grill allow them to bake indirect for 35-40 minutes or until the top is golden brown and crisp. If baking these in the oven let them bake for 20-25 minutes.

Variations

• Spice things up and add a diced, roasted jalapeno in with the poblanos.
• Switch up the cheeses. Any sharp English or Irish white cheddar works well in this recipe. Emmental and Jarlsberg are also great options. The parmesan can be replaced with asiago, Pecorino-Romano, Manchego, or Grana Padano. You can also use all parmesan or all Gruyère.
• Russet potatoes can be used instead of Yukon gold potatoes. If using russets make sure to peel them before slicing them.
• Bump up the fall and holiday flavors by adding a teaspoon of chopped sage leaves to the cream mixture.

Tips From the Beach

• These au gratin potatoes with poblanos are a great make ahead dish. Follow the directions up to baking. Allow them to cool completely before tightly wrapping the casserole dish in plastic wrap or foil. They will keep refrigerated for 2-3 days. You may need to add an additional ten minutes bake time if baking cold directly from the refrigerator.
• Stick to cheeses that are semi-firm and firm cheeses and avoid soft cheeses. This will prevent any unwanted greasiness.
• These potatoes can easily be reheated. Drizzle a little additional heavy cream over them and sprinkle a little additional grated parm over the top. Warm them up in a 350 degree oven for 15-20 minutes.

Potatoes Au Gratin with Poblanos

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Decadence takes center stage with these creamy, crispy, savory, and herbaceous Potatoes au Gratin with Poblanos that will have you diving in for seconds.

• Author: Nicole Stover
• Prep Time: 25
• Cook Time: 25
• Total Time: 50 minutes
• Yield: 4-6 1x
• Category: Side Dish
• Method: Baking
• Cuisine: American

Ingredients

Units USM Scale 1x2x3x

• 2 pounds Yukon gold potatoes, scrubbed, sliced into 1/8″ thin rounds, 6-8 potatoes
• 3 poblano peppers, roasted, peeled, deseeded, sliced into thin strips
• 1 large sweet onion, thinly sliced
• 3 garlic cloves, minced
• 2 tablespoons unsalted butter, plus extra for greasing the gratin dish
• 2 cups heavy cream
• 1 teaspoon kosher salt
• 1/4 teaspoon freshly cracked black pepper, plus extra for topping
• 1/2 teaspoon steak seasoning (can omit, but may need to add a little additional salt and pepper)
• 3–4 sprigs fresh thyme, plus 1 teaspoon chopped thyme leaves
• 2 bay leaves
• 2 teaspoons Dijon mustard
• 1 cup Gruyère cheese, grated
• 1/4 cup Parmigiano-Reggiano cheese, grated

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Instructions

1. Roast your poblano peppers. Prepare your grill for direct grilling. If using a gas grill heat the grill to 400 degrees. Place the peppers on the hot grate. Allow all sides to char, turning every 1-2 minutes. Remove the peppers from the grill and place them in a zip top bag or plastic container. Let them steam and cool. Remove the charred skin and seeds. Slice into thin strips. 
2. Preheat your oven or grill to 375. If making this on a charcoal grill prepare your grill for indirect cooking, baking the charcoal to the side. Butter a gratin dish or grill safe dish such as a cast iron skillet. Set aside.
3. Heat a large skillet over medium-high heat and add the butter, allowing it to melt. Add the onions and let them sauté until they’re translucent, about 5 minutes. Add the garlic and cook for 1 more minute.
4. Add the potatoes, thyme sprigs, bay leaves, seasonings, and heavy cream. Stir to combine. Let the cream come to a simmer, stirring often. Allow the potatoes to cook until fork tender and the cream has thickened, 10-15 minutes.
5. Remove the bay leaves and thyme sprigs. Stir in the poblano strips and Dijon mustard. Taste and adjust seasoning if needed.
6. Pour half of the potato mixture into the prepared gratin dish. Sprinkle the Gruyère cheese over the top. Pour the remaining potato mixture of the top. Sprinkle the parmesan over the potatoes. Top with a little additional cracked black pepper and the chopped thyme leaves.
7. Allow the potatoes to bake for 20-25 minutes in the oven, or 35-40 minutes indirect on the grill until the top is golden brown and crisp. 
8. Let cool for 10 minutes before serving. 

Notes

1. This can be assembled 2-3 days in advance. Tightly wrap the casserole dish with plastic wrap or foil and keep refrigerated. You may need to add an additional 10 minutes to the bake time if baking directly from the refrigerator, or you can allow it to come to room temperature before baking. 
2. Have fun using your favorite cheeses in this recipe. English and Irish style sharp white cheddars are delicious as well as cheeses like Jarlsberg and Emmental. Stick to semi-firm and firm cheeses for the best texture.
3. Russet potatoes can be substituted for the Yukon golds. Make sure to peel them first. They will have a slightly grainier texture.