Place 1/2 of the butter in each of two 8 inch, round, heat-resistant, non-metallic cake dishes.
Heat each dish, uncovered, on full power 30 seconds or until butter melts.
Blend 1/2 of the brown sugar with the melted butter in each dish.
Spread mixture evenly over bottom of the cake dishes.
Drain pineapple juice into a measuring cup and reserve.
Arrange pineapple slices and cherries over the brown sugar mixture in each dish.
Prepare cake mix according to package directions, substituting the reserved pineapple juice for the liquid called for on the package.
Add water if necessary for full measure.
Pour 2 2/3 cups batter over pineapple slices in both dishes.
Spread evenly.
Heat each layer, covered with clear plastic wrap, on roast for 9 to 10 minutes or until wooden pick inserted in center comes out clean.
Invert one layer onto serving plate.
Invert the second layer on top of the first.