Uses frozen burritos, or you could substitute your own. In a pinch, I've also used canned enchilada sauce, but it's better homemade! I use El Pato Mexican tomato sauce. If I have it on hand, I use queso fresco in addition to the shredded cheese.
Melt butter in a small saucepan. Stir in flour until smooth, then gradually add water. Bring to a boil; cook until thickened. Add tomato sauce, chili powder(s), garlic powder, bouillon, cumin, and salt. Simmer about 5 minutes more.
Place frozen burritos in a lightly greased 13x9 pan. Pour sauce over burritos. Top with cheese, olives and green onions.