Ingredients:
For the filling:
- 2 tbsp olive oil
- 1 tbsp butter
- 3 medium leeks, thinly sliced (white and light green parts)
- 1 medium onion, chopped
- 2 cloves garlic, minced
- 1 tsp dried thyme
- 1/2 tsp salt
- 1/4 tsp black pepper
- 2 tbsp all-purpose flour
- 1 1/2 cups milk (whole milk is best for richness)
- 1/2 cup vegetable broth
- 1 tsp Dijon mustard
- 1 cup grated cheddar cheese
- 1/2 cup grated Gruyère cheese (or another melty cheese)
- 6 medium potatoes, peeled and thinly sliced
For the pastry:
- 1 (14 ounce) package ready-made puff pastry, thawed
- 1 large egg, beaten
Instructions:
Make the filling:
- Heat the olive oil and butter in a large pot or Dutch oven over medium heat. Add the leeks, onion, garlic, thyme, salt, and pepper. Cook, stirring occasionally, for 10-12 minutes, until the vegetables are softened.
- Sprinkle the flour over the vegetables and cook for 1 minute more, stirring constantly.
- Gradually whisk in the milk and vegetable broth. Bring to a simmer, then reduce heat to low and cook for 5 minutes, stirring occasionally, until the sauce has thickened.
- Remove from heat and stir in the Dijon mustard, cheddar cheese, and Gruyère cheese until melted and smooth.
- Gently fold in the sliced potatoes.
Preheat oven:
- Preheat your oven to 400°F (200°C).
Prepare the pastry:
- Lightly flour a work surface. Roll out one sheet of the puff pastry to fit the bottom and slightly up the sides of a 9-inch pie dish.
- Trim any excess pastry and place the pastry into the dish.
Assemble the pie:
- Pour the cheesy leek and potato filling into the pastry-lined pie dish.
- Top with the second sheet of rolled-out puff pastry, trimming any excess. Crimp the edges to seal.
- Cut a few slits in the top pastry to allow steam to escape.
- Brush the top of the pie with the beaten egg.
Bake:
- Bake the pie for 35-45 minutes, or until the pastry is golden brown and the filling is bubbling. If the crust is browning too quickly, cover it loosely with foil.
Rest and serve:
- Let the pie rest for 10-15 minutes before slicing and serving. Enjoy!
Tips:
- For extra richness, substitute some of the milk with heavy cream.
- Feel free to experiment with different types of cheese. Parmesan, Fontina, or smoked Gouda would be delicious additions.
- If you don’t have puff pastry, you can use shortcrust pastry or even top the pie with mashed potatoes.
- Add a handful of fresh chopped herbs for a flavor boost.
