Preheat oven to 350 degrees F (175 degrees C). Drain pineapple and reserve 1/2 cup of the juice.
Melt butter in a 9 inch round pan. Arrange cherries and walnut halves in the pan according to how many servings you want. Sprinkle with brown sugar, and then pineapple.
Cream together shortening and granulated sugar until light and fluffy. Add egg and vanilla, and beat well. Sift together flour, baking powder and salt. Add alternately with reserved pineapple syrup, beating after each addition.
Spread batter in pan over pineapple. Bake at 350 degrees F (175 degrees C) for 45 to 50 minutes. Let stand 5 minutes in the pan, then invert onto plate. Serve warm.