Preheat oven to 350Whisk together the eggs with the milk, salt and pepper, then whisk in the goat cheese. Set aside.Heat an oven proof skillet over medium heat.When hot, add two tablespoons of olive oil.Add the onion and bell pepper, season with salt, pepper and red pepper flakes.Saute until starting to soften, about five minutesAdd the sausage and continue to cook, stirring occasionally, until sausage is browned.Add garlic and cook until fragrant, about 30 seconds.Brush the sides of the pan with olive oil, then pour in the egg mixture. Allow the eggs to cook on the stovetop until the edges start to set and pull away from the pan, about 5 minutes, then transfer to the oven.Keep a close eye on the frittata, bake until just set, about 20-30 minutes.Remove from oven and transfer frittata to a cutting board, allow to sit for a few minutes. Cut and serve.