Preheat oven to 375° and spray a muffin tin with non-stick cooking spray.
In a skillet, saute diced chicken in olive oil. Season with cumin, chili powder and salt. Add salsa verde after chicken is cooked through.
Prepare tortillas by cutting the rounded edges off, creating a square. Then cut into 4 squares per tortilla.
Tuck one tortilla square down into each muffin tin and fill with 1-2 Tbs of chicken mixture. Top with a teaspoon of cheese. Repeat with each cup.
Tuck remaining tortilla squares over down over the top of the chicken mixture and repeat the process. Fill with remaining chicken and top with cheese.
Using a pastry brush, coat the tortilla pieces that are sticking out of the tin, with melted butter. Bake for 18-20 minutes, or until tortillas turn golden.
Top with sour cream and guacamole and serve.