Lightly toast flour and nutritional yeast flakes in a saucepan over low heat. Gradually add vegetable broth until sauce becomes thick. Slowly add water and stir until sauce becomes smooth and slightly thick. Add remaining ingredients with the exception of the pasta. Stir well. Put cooked pasta in casserole dish and stir in sauce. Cover and bake at 350 degrees for 15 minutes and then cook uncovered for another 15 minutes.