Preheat the oven to 180°C (350°F), top and bottom heat.

Wash and trim the rhubarb, then cut the stalks into a decorative pattern.

In a mixing bowl, briefly combine all the batter ingredients. You can use a stand mixer, a hand mixer, or simply a whisk.

Do not overmix—just stir until the ingredients are incorporated.

Pour the batter into a springform pan and smooth the surface.

Arrange the rhubarb pieces on top and sprinkle with vanilla sugar.

Bake on the middle rack for about 35 minutes.

Let the cake cool on a wire rack and serve dusted with powdered sugar.