1. Preheat oven to 350º F.
2. Lightly coat eight 14-to 16-ounce individual baking dishes with cooking spray; set aside.
3. In large skillet cook onion in butter over medium-low heat about 15 to 20 minutes or until tender and golden brown, stirring occasionally.
4. Meanwhile, cook pasta in 4-quart Dutch oven according to package directions and add a whole Scotch Bonnet pepper pierced once or twice; drain and return to pan.
5. Add flour, salt, pepper & hot sauce (a couple of drops) to onion in skillet; stir until combined, about 1 minute. Add milk all at once. Cook and stir until slightly thickened and bubbly.
6. Gradually add chopped cheese; cook over medium-low heat until cheese melts. Stir into pasta. Fold in crab. Transfer to baking dishes.
7. Place bread pieces in food processor; cover and process to coarse crumbs. Sprinkle crumbs over pasta mixture.
8. Bake, uncovered, 20 to 25 minutes or until heated through and crumbs are golden brown. If desired, add a wedge of Brie to each dish the last 5 minutes of baking time.