Alfredo sauce can be made with soy milk instead of cow's milk. One recipe from PETA uses white beans and soy milk to create the creamy texture of Alfredo sauce.
For this recipe you need 1/4 vegan margarine, 2 cloves garlic, 2 cups white rinsed means, 1 1/3 cups unsweetened soy milk and parsley. In a medium saucepan, melt the margarine and sauté the garlic for a few minutes. Pour the mixture into a food processor with the white beans and 1 cup of the soy milk. Blend completely. If the sauce looks too thick, use the remaining soy milk. Pour the sauce back into the pan and season with the parsley as well as some salt and pepper.