Mash avocado in medium bowl. Add cream cheese, cumin, garlic powder, salt and pepper; blend well. Stir in tomatoes and chiles.
Sprinkle 3/4 cup of the Monterey Jack cheese on 4 of the tortillas. Top each with turkey slice. Spread avocado mixture over turkey. Top with remaining turkey slices. Sprinkle with 3/4 cup of the Cheddar cheese. Top with remaining tortillas.
Melt 1/2 tablespoon of the butter in 12-inch skillet over medium heat. Add 1 quesadilla; cook 2 to 4 minutes or until golden brown, turning once. Repeat with remaining butter and quesadillas. Garnish with remaining Monterey Jack and Cheddar cheese. Top each with olive slice.