Preheat oven to 350°. In a large bowl, combine flour, baking powder, salt, nutmeg and cinnamon. In a small bowl, combine sugar, oil, egg and milk; stir into dry ingredients just until moistened.
Fill greased or paper-lined muffin cups half full; place 1 teaspoon jam on top. Cover jam with enough batter to fill muffin cups three-fourths full. Bake until a toothpick comes out clean, 20-25 minutes.
Place melted butter in a small bowl; combine sugar and cinnamon in another bowl. Immediately after removing muffins from the oven, dip tops in butter, then in cinnamon sugar. Serve warm.