Preheat your oven to 400°F (200°C) and grease a muffin tin with cooking spray or butter.

In a large skillet, melt 2 tablespoons of butter over medium heat. Add 1 chopped onion and 2 minced garlic cloves, sautéing for 3-4 minutes until fragrant and translucent.

Add 2 cups of diced boneless, skinless chicken breasts and 1-2 cups of frozen mixed vegetables to the skillet; cook for 5-7 minutes until the chicken is no longer pink.

Pour in 1 cup of chicken broth and 1/2 cup of heavy cream, seasoning with salt, pepper, and 1 teaspoon of dried thyme. Simmer for about 5 minutes or until the filling thickens slightly.

Roll out 1 package of puff pastry on a floured surface and cut into squares for the muffin tin cups.

Press the pastry squares into the greased muffin tin. Spoon the chicken filling generously into each pastry cup.

Cover each filled pastry with another square of puff pastry, sealing the edges by pressing together. Brush the tops with a beaten egg.

Bake for 25-30 minutes until golden brown and puffed up.

Allow to cool for a few minutes, then gently release the edges with a butter knife and enjoy!