Place the biscuit mix in a large bowl. Combine the egg, bananas, brown sugar, milk, oil and vanilla; stir into biscuit mix just until combined. Fill paper-lined muffin cups two-thirds full.
Bake at 400° for 15-20 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Yield: 1 dozen.