1) Preheat oven to 350 degrees Fahrenheit.
2) Cook pasta according to directions. While pasta is cooking, begin making the casserole sauce. Melt the margarine in a large saucepan. Add the flour, salt, and pepper, and whisk over medium heat until roux begins to bubble. Slowly add soymilk while continually whisking. Turn the burner up to medium high and stir continually until sauce begins to thicken.
3) Once thick, combine the cooked pasta with sauce and pour into a 13x9" casserole dish. Top pasta mixture with broken up pieces of bread (I cover the entire surface)and bake for 20 minutes. Enjoy!
Source of recipe: This is a classic recipe from my childhood that my mother gave me and I veganized.