1. Heat oven to 350 degree F. With a knife or a teaspoon, gently scrape away the gills (the black portion underneath the caps) from mushroom caps.
2. Place mushrooms in a food processor with garlic, Italian seasoning, red pepper and salt and process until finely chopped but not pasty. Transfer mushroom mixture to a large bowl; combine with beef, bread crumbs, eggs, Worcestershire sauce and all but 2 tablespoons tomato paste. Gently press the mixture evenly into an 8x4x2-inch loaf pan, forming a rounded loaf. Spread remaining tomato paste over top. (Can be made ahead. Cover and refrigerate overnight.)
3. Bake, uncovered, 1 hour 10 minutes, or until an instant-read thermometer inserted in center of loaf registered 180 degrees F. Let meat loaf stand 10 minutes, then carefully unmold onto a cutting board and slice. Makes 4 to 6 servings.