A buttery brown sugar and fruit topping caramelizes right in the pan, then gets flipped onto a soft vanilla cake studded with blueberries. It's a one-pan dessert that looks like it came from a bakery.
Heat the oven to 350°F. Grease a 9-inch round cake pan and fit a parchment round into the bottom. Add the melted butter to the pan, spreading it over the parchment, and top with an even layer of brown sugar.
Lay the pineapple rings over the brown sugar in a single layer, without overlapping. Fill the gaps between the rings and the center of each one with the blueberries.
In one bowl, whisk the flour, baking powder, and salt together. In a second bowl, beat the softened butter and granulated sugar until light and fluffy, then add the eggs one at a time, followed by the vanilla. With the mixer on low, add the dry ingredients and milk in alternating additions, beginning and ending with the dry ingredients, mixing just until no streaks of flour remain. Spoon the batter over the fruit in the pan and smooth the top.
Bake for 40 to 50 minutes, until a toothpick inserted in the center comes out clean, tenting with foil near the end if the top is browning too fast.
Cool the cake in the pan for 10 minutes, then loosen the edges with a knife and turn it out onto a plate. Allow it to cool a bit longer before cutting into it.
Notes
If using canned pineapple rings, drain and pat them very dry before arranging them in the pan, or the topping will turn watery instead of caramelizing.Invert the cake onto the serving plate while it's still warm. If it sits too long, the caramel can set and stick to the pan.
All nutritional information provided is an estimate. For specific dietary needs or concerns, we recommend consulting a nutrition calculator or a qualified expert.