Combine butter, garlic, salt and pepper in a small bowl.
Slice 1 potato crosswise, leaving about 1/2 inch at the bottom still attached. (Place pencils on each side of the potato when cutting to ensure that you don’t slice all the way through.) Smear with butter mixture, carefully working it between the slices and coating all sides.
Repeat for remaining potatoes.
Place potatoes on a nonstick baking sheet and bake 45 minutes or until golden brown and tender.