Place a large skillet over medium high heat. Add the olive oil to warm up until glistening, about 1 minute.

Add the chopped onion and minced garlic to saute for 2-3 minutes, until tender and fragrant.

Add the ground beef, season with the salt and black pepper, then saute until browned, about 5-7 minutes. Break up the meat with a wooden spoon.

Add the thinly sliced mushroom, Worcestershire sauce, and thyme to cook until all moisture from the mushrooms has evaporated, about 4-5 minutes.

Remove from heat to cool for 20-30 minutes, until room temperature.

Preheat oven to 425F. Line large baking pan with parchment paper.

Dust the parchment paper lightly with flour.

Place one sheet of thawed puff pastry on the baking pan. Slice into 4-6 equal squares/rectangles.

Add a generous serving of the cooled beef filling into the center of each.

On a lightly floured surface, divide the remaining puff pastry sheet into similar sizes to match the others. Place on top of each filled puff pastry square. Crimp the edges with a fork. Score the top with 2-3 small slits on top.

Place the baking pan in the freezer for 10-15 minutes.

Afterwards, brush each top with an egg wash then sprinkle with sesame seeds.

Bake until deeply golden brown, about 20-25 minutes. Best enjoyed while warm.