Grease a deep 9” round cake pan (I used a springform pan, but please make sure your’s is leak proof or your oven will be a mess).
Arrange the plums around the pan however you wish. Mine didn’t cover the entire pan because I didn’t have enough, but the more the better.
Melt the butter in a small saucepan, add the brown sugar and syrup (if using) and cook on low heat just until combined and smooth (do not allow to simmer).
Pour the sugar mixture over the plums and set aside.
Sift together the flour, baking soda, baking powder, sugar, and salt and add to a mixer or food processor.
Add the oil, egg, sour cream, milk vanilla, nutmeg & cinnamon on at a time. After each addition, beat until well blended.
Pour the batter evenly over the pan to cover the plums.
Bake 1 hour or until a tester comes out clean.
Let the cake cool for 20-30 minutes in the pan. Place a serving plate over the cake and invert the pan, lifting it to reveal the pineapple now on top. Serve warm or at room temperature.
Please note – this recipe uses Golden Syrup is common in English baking and I’ve fallen in love with it since moving here. I know it can be hard to find in the US, so you can buy it here on Amazon.(As an Amazon Associate, a small commission is made from qualifying purchases).
I used a springform pan, but please make sure your’s is leakproof or your oven will be a mess!