Preheat your oven to 400°F (200°C).

Divide the ground beef into four portions and season with salt and pepper. Shape into patties slightly larger than cheese slices.

Place a slice of cheddar cheese on top of each patty. Optionally add another layer of ground beef on top of the cheese.

Roll out the puff pastry to ¼-inch thick and cut into squares large enough for the patties.

Position each patty in the center of a pastry square, fold over, and seal the edges with water.

Arrange the sealed patties on a baking sheet, seam-side down, ensuring space between each.

Beat the egg and brush over the top of each Wellington for a golden finish.

Bake for 20-25 minutes until puffed and golden brown.

Let rest for 5 minutes before slicing in half to serve.

Serve warm with toppings like lettuce, tomatoes, and condiments.