Combine butter and brown sugar in (8x8 inch) baking dish. Microwave 1-1/2 to 2 minutes on HIGH, or until butter and sugar melt. Stir. Arrange pineapple and cherries in syrup.

Blend cake mix, pineapple juice and eggs in medium mixing bowl on low speed of electric mixer. Beat on medium speed for two minutes. Pour evenly over fruit. Micro 8-1/2 to 10 minutes on HIGH, or until wooden pick inserted in center comes out clean. (Rotate dish 1/2 turn after 5 minutes) Immediately invert onto serving plate and remove dish. Cool