Put a large pot of water on stove to boil. Put vegetables into boiling water; cook for 2 minutes or until colors intensify. With a slotted spoon, transfer veggies to a paper towel–lined plate. Then put penne into the boiling water; cook according to package directions. In a saucepan, heat evaporated milk over medium heat for 1 minute. Whisk in Parmesan and then flour until smooth; season with salt and pepper. Stir in vegetables and pasta. Serve hot.