In a bowl, cream butter and brown sugar. Add eggs, one at a time, beating well after each addition. Stir in cereal. Combine milk and vanilla. Combine flour, baking powder and salt; add to creamed mixture alternately with milk mixture, beating just until moistened.
Fill paper-line muffin cups two-thirds full. Bake at 400° for 13-15 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack.