In a large mixing bowl, combine the eggs and sugar, whisking until smooth and pale, about 2-3 minutes.

Add the ricotta cheese, olive oil, and vanilla extract to the egg mixture. Mix until lump-free, about 2 minutes.

Sift the flour, baking powder, and salt into the wet mixture. Fold gently until no dry flour remains.

Chop the plums into small pieces and fold them into the batter until combined.

Grease a 9-inch springform pan and line the bottom with parchment paper.

Pour the batter into the prepared pan and optionally top with extra plum slices.

Preheat the oven to 350°F (175°C) and bake for 50-60 minutes until golden and a toothpick comes out clean.

Cool in the pan for 15 minutes, then remove the springform and cool completely on a wire rack.

Slice and serve the cake warm or at room temperature, possibly with whipped cream.