In a casserole, melt margarine and sauté onion ... Simmer, while stirring continuously, until mixture thickens. 4. Add cooked macaroni and tuna. Mix well. Transfer to greased oven-proof dish.
Drain fat. Return pot to heat and add diced tomatoes, kidney beans, chili powder, cumin, cayenne, chicken broth, and pasta and bring to a simmer. Simmer until pasta is al dente, 14 to 15 minutes.