Beat shortening and 1/2 cup sugar at medium speed with an electric mixer until creamy. Add egg, beating until blended.
Combine flour, baking powder, and salt. Add to shortening mixture alternately with pineapple, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Spoon into greased muffin pans, filling two-thirds full.
Bake at 350° for 25 minutes or until golden. Remove from pans immediately, and brush with melted butter. Stir together remaining 1/2 cup sugar and ground cinnamon; sprinkle over muffins. Serve hot.