In a large saucepan, melt butter. Stir in flour until smooth; gradually add water. Bring to a boil; cook and stir for 1 minute or until thickened. Stir in chili powder and garlic salt. Bring to a boil. Reduce heat; simmer, uncovered, for 10 minutes.
In a large skillet over medium heat, cook the beef, sausage and onion until meat is no longer pink, breaking it into crumbles; drain. Stir in refried beans; heat through.
Spread 1/4 cup sauce in a greased 13x9-in. baking dish. Spread 1 tablespoon sauce over each tortilla; place 2/3 cup meat mixture down the center of each tortilla. Top each with 1/4 cup cheese. Roll up and place seam side down in baking dish. Pour remaining sauce over the top; sprinkle with remaining cheese.
Bake, uncovered, at 350° for 18-22 minutes or until bubbly and cheese is melted. Serve with optional toppings as desired.