Melt butter in a 10-inch cast iron skillet; sprinkle brown sugar evenly over butter. Arrange 7 pineapple slices on sugar. Cut remaining pineapple slices in half; line sides of pan, keeping cut sides up. Place a cherry in the center of each whole pineapple slice; arrange walnuts between slices.
Combine shortening, butter, and orange rind; cream well. Gradually add 2/3 cup sugar, beating until light and fluffy. Add egg: beat well.
Combine flour, baking powder, and salt; add to creamed mixture alternately with milk, beginning and ending with flour mixture. Beat well after each addition. Stir in coconut and vanilla.
Spoon batter evenly over pineapple slices in prepared skillet. Bake at 350° for 45 minutes or until a wooden pick inserted in center comes out clean. Cool in skillet 10 minutes, and invert cake onto serving plate.
Serve warm with a dollop of whipped cream, if desired.