This quick and easy recipe for Strawberry Rhubarb Upside-Down Cake is perfect for a summer dessert. The cake is moist and fluffy, and the combination of sweet strawberries and tart rhubarb is a match made in heaven. To make the cake, simply mix together the dry ingredients, cream the butter and sugar, and then add the eggs and vanilla. Pour the batter over the fruit and bake for 35-40 minutes. Once the cake is done, flip it over onto a serving platter and enjoy!