Equipment
Ingredients
Vegetable Filling
- 15 ml olive oil
- 150 g leeks, cleaned and sliced
- 150 g carrots, peeled and diced
- 200 g waxy potatoes, peeled and diced
- 100 g frozen peas
- 2 garlic, minced
Gruyere Cheese Sauce
- 50 g unsalted butter
- 50 g all-purpose flour
- 250 ml vegetable stock, warm
- 250 ml whole milk, warm
- 120 g gruyere cheese, freshly grated
- 30 g parmesan cheese, freshly grated
- 10 g dijon mustard
- 5 g fresh thyme, leaves only, chopped
Pastry and Finish
- 320 g puff pastry, thawed in refrigerator
- 1 egg, beaten
Nutrition (per serving)
Method
Preheat your oven to 200°C/400°F. Ensure your oven racks are positioned in the middle.
Heat the olive oil in a large skillet over medium heat. Sauté the leeks, carrots, potatoes, and garlic until the vegetables begin to soften but are not fully cooked, about 8 to 10 minutes.
In a separate medium saucepan, melt the butter over medium heat. Add the flour and whisk constantly for 1 to 2 minutes to create a roux, cooking out the raw flour taste without letting it brown.
Gradually whisk the warm vegetable stock and whole milk into the roux. Bring the mixture to a gentle simmer and cook for 5 minutes, whisking frequently, until the sauce thickens and coats the back of a spoon.
Remove the saucepan from the heat. Stir in the grated Gruyere, Parmesan, Dijon mustard, and chopped fresh thyme until the cheeses are completely melted and the sauce is smooth.
Fold the sautéed vegetables and the frozen peas into the cheese sauce until evenly distributed. Pour this filling into your deep pie dish.
Unroll the puff pastry sheet and drape it over the pie dish, ensuring it covers the filling completely. Trim any excessive overhang and crimp the edges tightly against the rim of the dish.
Brush the surface of the pastry evenly with the beaten egg wash. Using a sharp knife, score three small slits in the center of the pastry to act as vents for steam.
Bake in the preheated oven at 200°C/400°F for 25 to 30 minutes, or until the pastry is puffed, deeply golden brown, and the filling is bubbling around the edges.
Remove the pie from the oven and let it rest for 10 minutes before serving. This allows the sauce to thicken up slightly and prevents it from being too runny when scooped.
Chef's Notes
- To achieve maximum flakiness in your puff pastry, keep the dough as cold as possible. If the kitchen is warm, pop the assembled, unbaked pie into the refrigerator for 15 minutes before baking.
- Warming the milk and vegetable stock before adding them to your roux ensures a silky, lump-free bechamel base.
- A spoonful of Dijon mustard is essential for cutting through the richness of the cheese sauce. It acts as an emulsifier and amplifies the savory notes of the Gruyere without tasting distinctly of mustard.
- If you prefer a thicker sauce, you can let the filling cool completely before topping it with pastry; a chilled filling supports the pastry better and yields thicker slices.
Storage
Refrigerator: 3 days — Keep covered in an airtight container.
Freezer: 1 month — Freeze unbaked. Bake directly from frozen, adding 15-20 minutes to the baking time.
Reheating: Reheat in a 175 C / 350 F oven for 15-20 minutes to re-crisp the pastry. Microwaving is not recommended as it will make the pastry soggy.
