Preheat oven to 450 (F). Whisk together the Maille Mustard and Mayonnaise Add Salt to taste. In a skillet heat 3 Tbl. Of oil, add red pepper flakes and cook, stiring 10 seconds. Add garlic and rosemary and cook, stirring for 30 seconds. Stir in bread crumbs, salt and pepper to taste and remove skillet from heat. In a large skillet heat remaining oil over moderately high heat, add lamb sprinkled with salt and pepper and brown well on all sides. Transfer lamb to shallow roasting pan, Spread mustard mixture on meaty side and press crumbs on top of mustard mixture. Bake for 15 minutes for medium rare meat. Transfer lamb to a cutting board and let stand for 10 mintues before carving. Serves 4