Preheat oven to 425°.
Cook lamb, onion, and garlic in a nonstick skillet over medium-high heat until lamb is browned, stirring to crumble. Drain. Return lamb mixture to pan. Stir in Italian seasoning, salt, and black pepper.
Unroll pizza crust onto an ungreased baking sheet. Cut dough into 4 quarters, using a sharp knife or pizza cutter. Pat each quarter into a 6 x 5-inch rectangle.
Spoon lamb mixture evenly in center of each rectangle; sprinkle with cheese and red pepper. Bring opposite corners of rectangles together, pinching to seal. Pinch all seams together to completely enclose lamb mixture.
Bake at 425° for 13 minutes or until lightly browned. Serve with marinara sauce.