In a large bowl, mix the first seven ingredients. In another bowl, whisk together the egg, milk and olive oil. Add to flour mixture; stir just until mixture is moistened. Fold in the cheddar cheese and tomatoes.
Fill greased muffin cups three-fourths full. Bake at 375 for 18-20 minutes or until a toothpick inserted in center comes out clean. Cool for five minutes before removing muffins from plan to a wire rack. Serve warm!