Cottage Pie Lattice Top with Root Vegetables

Preheat oven to 400°F (200°C).

In a large skillet, brown the ground beef over medium-high heat. Drain off any excess grease.

Add the diced onion, carrots, parsnip, and celery to the skillet and cook until softened, about 5-7 minutes.

Stir in the minced garlic and cook for another minute until fragrant.

Sprinkle the flour over the beef and vegetables and cook for 1 minute, stirring constantly.

Gradually pour in the beef broth, stirring to prevent lumps. Add the tomato paste, Worcestershire sauce, thyme, salt, and pepper. Bring to a simmer and cook for 10-15 minutes, or until the sauce has thickened slightly.

While the beef mixture simmers, cook the potatoes in a medium saucepan of boiling salted water until tender, about 15-20 minutes. Drain the potatoes and return them to the saucepan.

Add the butter and milk to the potatoes and mash until smooth and creamy. Season with salt and pepper to taste.

Pour the beef and vegetable mixture into a 9x13 inch baking dish.

Roll out the thawed puff pastry on a lightly floured surface. Cut the puff pastry into strips, about 1 inch wide.

Arrange the pastry strips over the beef mixture in a lattice pattern. Trim any excess pastry from the edges of the baking dish.

Whisk the egg yolk with a tablespoon of water. Brush the lattice crust with the egg wash for a golden brown finish.

Spoon or pipe the mashed potatoes evenly over the lattice crust.

Bake in the preheated oven for 25-30 minutes, or until the crust is golden brown and the filling is bubbly.

Let the Cottage Pie Lattice Top with Root Vegetables cool for a few minutes before serving.