Meanwhile, in 10-inch skillet, melt 2 tablespoons of the butter over medium heat. Add carrot; cook and stir 3 minutes. Add zucchini; cook and stir 2 to 3 minutes or until just tender. Add garlic; cook and stir 30 seconds. Add flour, salt, pepper, nutmeg and pepper flakes; cook and stir 1 minute. Gradually stir in milk. Heat to boiling, stirring constantly. Boil and stir 1 minute. Add spinach; stir until wilted. Remove from heat; stir in cheeses until melted. Stir in pasta; pour mixture into pan.