Preheat oven to 400°.
Sprinkle tenderloin with pepper. Coat a large nonstick skillet with cooking spray; place over medium-high heat until hot. Add beef, and cook 10 minutes or until browned.
Combine mustard and horseradish; spread onto beef. Combine breadcrumbs and remaining 5 ingredients; pat onto beef, pressing firmly. Coat beef with cooking spray. Insert meat thermometer into center of beef. Bake at 400° for 35 to 40 minutes or until temperature registers 145° (medium-rare) to 160° (medium).
Place beef on a platter; cover with foil. Let stand 10 minutes before slicing. YIELD: 7 servings (serving size: 3 ounces cooked beef)