Preheat the oven to 180C / 350 F.
Melt the butter and pour it into a 7 inch round pan . Turn the pan so that the butter slightly coats the sides as well. Sprinkle the sugar on top of the butter on the bottom of the pan.
Neatly lay the slices of pineapple in a pattern that you want, with the neater side facing down. Place cherries , if using , in the gaps in between.
In a large bowl , using an electric mixer or whisk , beat together all ingredients until light and fluffy. Pour batter over the pineapples . Smooth the top .
Bake for 50-55 minutes until a tooth pick inserted comes out clean . Cool in pan for 5 minutes.
Place the serving plate over pan and carefully invert the pan. let rest for 5 minutes. Carefully remove pan , and place any dislodged or stuck fruit back on cake.
Serve !