Leek and Smoked Potato Gratin with Gruyère

By AislePrompt Editorial · Published 2026-04-06 · Updated 2026-04-06

How this recipe was made — this recipe was drafted by AislePrompt's AI-assisted pipeline from technique templates and USDA-sourced nutrition data, and published by AislePrompt Editorial — see how AislePrompt recipes are developed and reviewed.

A comforting Flemish comfort food featuring creamy leeks and potatoes baked in a rich cheese sauce with a golden crust, perfect with a simple green salad. This Belgian-inspired vegetarian recipe, ready in about 75 minutes, pairs small leeks, russet potatoes, unsalted butter for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 380 calories and feeds 6, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 25 min Cook: 50 min Serves 6 Belgian cuisine 380 cal/serving

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Ingredients

3, white and light green parts, thinly sliced small leeks
2 medium, thinly sliced russet potatoes
4 tbsp unsalted butter
3 tbsp all-purpose flour
2 cups whole milk
1 cup, grated Gruyère cheese
1 tsp smoked paprika
1 tbsp, chopped fresh thyme
1 tsp salt
1/2 tsp freshly ground black pepper

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Instructions

Step 1: Preheat oven to 375°F (190°C). Butter a 9x13-inch baking dish.
Step 2: Melt 2 tbsp butter in a medium saucepan over medium heat. Whisk in flour and cook for 1 minute until golden. Gradually whisk in milk, stirring constantly until thickened (about 5 minutes).
Step 3: Remove from heat. Stir in 1/2 cup Gruyère, smoked paprika, thyme, salt, and pepper until melted. Set aside.
Step 4: Layer half the potatoes and half the leeks in the baking dish. Pour half the cheese sauce over them. Repeat layers with remaining potatoes and leeks.
Step 5: Pour remaining cheese sauce evenly over the top. Sprinkle with remaining 1/2 cup grated Gruyère.
Step 6: Bake uncovered for 45-50 minutes until golden brown and bubbly around the edges. Let rest for 10 minutes before serving.