Meanwhile, heat the olive oil in a Dutch oven or large saute' pan over medium heat. Add the garlic and red pepper flakes and cook until just fragrant, about 30 seconds. Stir in the tomato sauce, water, tomato paste, salt, pepper, sugar and butter. Heat, while stirring, until the butter is melted. Slowly stir in the milk, then turn the heat to low. Simmer at low heat for 10 minutes.