Preheat the oven to 350 degrees Fahrenheit and spray a 9×13 baking dish or 9-inch round cake pan with nonstick spray. Set aside for later.
In a medium bowl, sift together the dry ingredients (all-purpose flour, cornstarch, baking powder, and salt). In a separate bowl, cream the butter and sugar until light and fluffy, about 2 minutes. Add the eggs and egg yolks, followed by the oil and vanilla extract, mixing between each addition until just combined.
Add the flour in three additions, alternating with the milk between each addition. It will look like this: 1/3 flour, mix, 1/2 milk, mix, 1/3 flour, mix, 1/2 milk, mix, 1/3 flour, mix.
Melt the remaining stick of butter in a microwave-safe bowl and pour it into the prepared baking dish. Sprinkle with the brown sugar, then arrange the pineapple rings and cherries as desired (you can copy how I arranged mine or get creative with different patterns).
Carefully pour the cake batter over the topping in an even layer.
Transfer to the oven and bake for 35-45 minutes or until a toothpick inserted in the middle comes out clean.
Remove the cake from the oven and allow it to cool for at least 30 minutes before inverting. This allows time for the topping to set.
Carefully slide a sharp knife around the edges of the cake to loosen any stuck bits. Place a shallow baking pan, cutting board, or serving tray upside down on top of the cake pan. Then, tightly grab both sides, flip the cake upside down, and gently tap the pan to release the cake.
Slice and serve with homemade whipped cream, Cool Whip, or ice cream, if desired.