In a large bowl, combine flour, sugar, baking powder and salt. Cut in peanut butter and 2 tablespoons butter until the mixture resembles coarse crumbs. Beat the eggs and milk; stir into the dry ingredients just until moistened. Fill greased or paper-lined muffin cups two-thirds full.
Bake at 400° for 15-17 minutes or until muffins test done. Melt remaining butter; brush over the tops of muffins. Sprinkle with cinnamon-sugar. Cool for 10 minutes; remove to a wire rack. Serve with jelly if desired.