Spinach Quesadillas

In a large nonstick skillet, cook and stir first 6 ingredients until spinach is wilted. Remove from heat; stir in cheeses., Top half of each tortilla with spinach mixture; fold other half over filling. Place on a griddle coated with cooking spray; cook over medium heat until golden brown, 1-2 minutes per side. Cut quesadillas in half; if desired, serve with sour cream.