If there’s a side dish that feels as cozy as a blanket and as indulgent as a holiday, it’s got to be a gratin. This Brussels and Potato au Gratin combines creamy, cheesy layers of sliced potatoes with the sweet, nutty flavor of shredded Brussels sprouts. Baked to golden perfection, it’s a true crowd-pleaser and a warming addition to any dinner table.
Why We Love Brussels and Potato au Gratin
Adding Brussels sprouts to a classic potato gratin gives it a pop of green color and extra flavor that balances the creaminess of the potatoes. Brussels sprouts bring a subtle nuttiness that works perfectly with the blend of gruyere, cheddar, and parmesan, giving every bite a delightful mix of textures and tastes.
How to make Brussels and Potato au Gratin
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Prepping the Ingredients: Begin with fresh Brussels sprouts and russet potatoes. The sprouts are trimmed, cored, and finely shredded, while the potatoes are thinly sliced to ensure even cooking and a tender bite.
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Making the Cheese Sauce: The key to this gratin is a creamy cheese sauce made with a simple roux. This classic technique involves cooking flour with melted butter and aromatic ingredients (like shallots and garlic) until lightly golden, which brings out a deeper flavor. Whole milk is gradually added, making a rich sauce that thickens as it simmers. Adding in a combination of gruyere, cheddar, and parmesan cheeses infuses it with rich, savory notes and the perfect amount of melt.
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Layering the Dish: The gratin is layered with sliced potatoes, shredded Brussels sprouts, and cheese sauce, repeating for two layers to achieve a balanced texture. With each layer, the flavors blend further, creating a harmonious mix as it bakes.
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Baking: Covering the gratin for the first part of the bake keeps everything moist and tender, while uncovering it towards the end allows the cheese on top to brown and bubble to perfection.
Serving Suggestions
Once it’s baked to a golden, bubbly finish, this gratin is beautiful enough to stand alone but works as a versatile side to roasted meats, fish, or a hearty vegetarian main. Serve it warm, straight from the baking dish, and watch as everyone digs in for second helpings!
Tips for Success
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Consistent Slicing: For the potatoes to cook evenly, aim to slice them as uniformly as possible. A mandoline slicer is especially helpful here.
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Freshly Grated Cheese: Pre-grated cheese often contains anti-caking agents that can affect the melt. Freshly grating the gruyere, cheddar, and parmesan ensures a smoother sauce and richer flavor.
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Taste as You Go: Season the cheese sauce to taste with salt and pepper before layering. Adjust the seasoning if needed, as this will be the primary flavor in the final dish.
Brussels and Potato
Ingredients
- 4 large russet potatoes
- 1.5-2lbs brussels sprouts
- 1 large shallot, finely minced
- 3 cloves garlic, minced
- 4 tbsps unsalted butter
- 1/4 cup all-purpose flour
- 4 cups whole milk
- 6 oz gruyere cheese, grated
- 4 oz cheddar cheese, grated
- 1/2 cup grated parmesan
- salt and pepper
Instructions
- Grease a 9x13 baking dish, or large cast-iron skillet, and set aside.
- Trim the bottom stem of each brussels sprout, discard any outer leaves, remove core and thinly shred. Set aside in a bowl. Peel potatoes and cut into 1/8 inch slices (mandoline slicers are great for this). Set potatoes aside.
- Preheat oven 375°F. Over medium heat, melt butter in a medium pot. Add shallot and cook for 2 minutes. Add garlic and cook until fragrant, 1 minute. Whisk flour into butter until no flour pockets remain. Continue to whisk to prevent from burning and to allow flour to slightly cook until turns a light golden brown (2-3 minutes). This helps to get rid of the raw flour taste.
- Gradually pour in milk and continue to whisk for a few more minutes, allowing the sauce to thicken to a creamy consistency. You know the sauce is ready when it can coat the back of a spoon. Season with salt and pepper. Turn off the heat and add in 3/4 of the gruyere cheese, half the cheddar, and half of the parmesan.
- To your prepared baking dish, layer the bottom with potatoes by overlapping them (about half of the potatoes). Then evenly scatter half of the shredded brussels sprouts. Scoop on half of the cheese sauce. Repeat another layer of potatoes, brussels and cheese sauce then sprinkle on the remaining cheese. Loosely cover the top with foil and bake covered for 30 minutes. Uncover then bake for additional 30 minutes, or until potatoes are fork tender and top is golden/bubbly. Remove from oven and allow to cool slightly before digging in. Enjoy!
