How to Make It
Trim away outer leaves from cauliflower head. Cut head in half lengthwise; cut a 1-inch-thick “steak” from each cauliflower half. Set steaks aside.
Cut remaining cauliflower (about 12 ounces) into small pieces. Place in a saucepan with 1/2 cup water and garlic; bring to a boil over high. Reduce heat to medium-low, cover, and cook 15 minutes or until very tender. Remove from heat; let stand while you prepare steaks.
Meanwhile, place cornstarch in a shallow dish. Combine 2 tablespoons milk and egg in another shallow dish. Combine flour, garlic powder, onion powder, paprika, and 1/2 teaspoon pepper in a third shallow dish. Dredge one cauliflower steak in cornstarch; shake off excess. Dip in egg mixture; dredge in flour mixture, shaking off excess. Repeat with other cauliflower steak. Discard remaining cornstarch, egg mixture, and flour mixture.
Heat a large nonstick skillet over medium. Add 2 tablespoons oil; swirl to coat. Add cauliflower steaks to pan; cook 4 to 5 minutes or until browned on bottom. Remove steaks from pan, browned side up. Add remaining 1 tablespoon oil to pan; swirl to coat. Return steaks to pan, browned side up; cook 4 to 5 minutes or until browned on bottom. Sprinkle evenly with 1/4 teaspoon salt.
Drain steamed cauliflower pieces; place in a blender. Add 1/2 cup milk, remaining 1 teaspoon pepper, and remaining 1/4 teaspoon salt. Blend until very smooth. Serve over cauliflower steaks.