Preheat oven to 350°F (177°C).

Prepare topping first: Pour ¼ cup melted butter into an ungreased 9×2 inch pie dish or round cake pan. Sprinkle brown sugar evenly over butter. Blot excess liquid off the fruit and arrange about 6-7 pineapple slices and all the cherries on top of the brown sugar. Place pan in the refrigerator for a few minutes.

Make the cake batter: Whisk together cake flour, baking powder, baking soda, and salt. Set aside.

Beat the butter on high speed until smooth and creamy, add sugar and beat until creamed together. Beat in egg whites, sour cream, and vanilla extract. Pour the dry ingredients into the wet ingredients, then slowly pour in pineapple juice and milk. Mix until combined.

Remove topping from the refrigerator. Pour and spread cake batter evenly over topping.

Bake for 43-48 minutes, tenting foil on top halfway through to prevent over-browning. The cake is done when a toothpick inserted comes out mostly clean.

Remove cake from the oven and cool on a wire rack for 20 minutes. Invert the cake onto a cake stand or serving plate.

Cool completely at room temperature before slicing and serving. Store leftover slices for up to 3 days in the refrigerator or 3 months in the freezer.