In a skillet, melt butter over medium heat. Add onion and cook 3 minutes until softened. Whisk in all-purpose flour and cook 1 minute, stirring constantly.

Slowly whisk in chicken broth and milk or half-and-half, stirring until smooth. Simmer until thickened, about 4 minutes.

Stir in cooked chicken, potatoes, peas and carrots, dried thyme, salt, and black pepper. Cook 2 minutes, then remove from heat and let cool slightly while you prep the crusts.

Unroll the pie crust on a lightly floured surface. Using a 3-inch round cutter, cut 12 rounds for the bases and 12 smaller rounds (about 2 inches) for the tops, re-rolling scraps as needed.

Press the larger rounds into each mini muffin cup, gently pushing up the sides to form a little cup.

Spoon about 1 tablespoon of filling into each crust cup. Top with the smaller dough rounds, pressing the edges lightly to seal. Cut a small slit in each top for venting.

Brush tops with egg wash. Bake for 15 minutes or until golden brown and crusts are cooked through.