Prep Your Dish

Grease a 9×13-inch baking dish with butter or nonstick spray. If you want to serve individual portions, use small ramekins — just reduce bake time slightly.

Slice the Potatoes

Peel and thinly slice your russet potatoes using a mandoline for consistent thickness. Even slices ensure the dish cooks uniformly and achieves that classic melt-in-your-mouth tenderness.

Clean and Slice the Leeks

Cut off the dark green tops and root ends. Slice the leeks lengthwise and rinse under cold water to remove grit. Use only the white and light green parts, sliced thinly.

Sauté the Aromatics

In a large skillet, melt butter over medium-high heat. Add jalapeños, leeks, salt, and pepper, and cook for about 4–5 minutes until softened and fragrant. The aroma will be savory and slightly sweet.

Make the Creamy Cheese Sauce

Pour in the heavy cream and half & half, then bring the mixture to a gentle simmer. Stir frequently so it doesn’t scorch. Once warm, remove from heat and add the cheddar and Monterey Jack cheeses, stirring until smooth and velvety.

Layer the Potatoes and Sauce

Add a layer of sliced potatoes to the prepared dish, followed by a ladle of cheese sauce. Repeat the process — layer, sauce, layer — finishing with a final coating of sauce on top.

Bake to Perfection

Cover the dish with foil and bake at 350°F (175°C) for 1 hour. Then uncover and bake for an additional 15–20 minutes until the top turns golden brown and bubbling. Let it rest for at least 10 minutes before serving to allow the sauce to thicken.