1. Preheat the oven to 375°F (190°C). Line an 8 inches (20cm) springform tin with baking parchment and grease lightly. Melt the butter and let cool down slightly. Wash and dry the plums, cut them in half, and remove the stones.

2. Add the ricotta, sugar (or xylitol), and lemon zest to a large bowl and mix for about 2-3 minutes until soft and creamy. Add the eggs one at a time and mix well after each addition. Next, add the melted butter and mix until well combined. Mix flour, baking powder, and salt and add to the bowl – stir until just combined. Transfer the batter to the prepared baking tin and smooth out the top. Distribute the halved plums evenly on top and sprinkle with some brown sugar. Bake for about 50-60 minutes or until a wooden skewer inserted into the center of the cake comes out clean. Take out of the oven and let cool down completely on a wire rack. Serve with some whipped cream.