Preheat oven to 375.

Heat oil in a large skillet over medium-high heat.

Season chicken pieces well with garlic powder, salt, pepper, chili powder and cumin.

Add chicken to hot skillet and cook, undisturbed until browned and easily releases from the pan, 3-4 minutes.

Add onion and stir chicken and cook, stirring occasionally, 3 more minutes.

Add ⅔ cup salsa and beans and bring to a simmer.

Reduce heat slightly and cook, stirring occasionally until slightly thickened and creamy, about 5 minutes.

Brush sides and bottom of an 11 x 7 baking pan or baking dish with butter.

Working with 1 tortilla at a time, use remaining butter to brush one side of each tortilla and place in dish.

Place about 1 tablespoons of cheese in bottom of the tortilla and top with about ⅓ cup filling and a couple more tablespoons of cheese.

Fold tortilla up like a taco and place it against the edge of the pan.

Place a second buttered tortilla against the next one and top with cheese and filling.

Fold in half and repeat with remaining tortillas, filling and cheese to fill the baking dish with side by side tacos.

Top with any remaining cheese.

Bake 20-25 minutes or until tops of each tortilla are golden brown and toasted and cheese is melted and bubbly.

Meanwhile, stir together remaining salsa with sour cream until well combined.

Top with lettuce just before serving and serve topped with sour cream sauce.