In a large nonstick skillet, brown ground beef over medium heat 8-10 minutes or until no longer pink, stirring occasionally. Pour off drippings. Season beef with chili powder, cumin, salt and pepper. Stir in spinach and salsa; heat through. Remove from heat; stir in cheese. To serve, spoon 1/2 cup beef mixture in center of each tortilla. Fold bottom edge up over filling; fold right and left sides to center, overlapping edges. Makes 8 burritos.