In a small saucepan, saute the onion and green pepper in 2 tablespoons butter. Stir in flour until blended; gradually stir in the milk. Add chili powder and salt. Bring to a boil; cook and stir for 1 minute or until thickened.
Remove from heat; stir in the crab, mayonnaise and hot pepper sauce. Transfer to a greased shallow 1-qt. Baking dish.
Melt the remaining butter and toss with bread crumbs. Sprinkle over crab mixture. Bake uncovered at 350F for 25-30 minutes or until heated through. Sprinkle with paprika.