
Cook macaroni in boiling, salted water until almost tender but still firm. Drain and set aside.
Heat butter in a large saucepan until melted; add chopped onion and garlic and cook until softened, about 3 minutes. Stir in flour and cook, stirring, until golden, about 2 minutes. Whisk in the milk and cook, stirring, until thickened, about 5 minutes.
Remove from heat, add salt and pepper to taste, stir in grated cheese. When cheese is melted, stir in tomatoes, macaroni and Isadora Beans. Top with crumbled corn chips.
Bake at 350° F until golden brown and bubbling, about 25-30 minutes.