Wash and dry 200g of fresh blueberries, ensuring no excess moisture remains.

Puree the blueberries with 30ml water, then simmer with 40g sugar and 4g cornstarch, stirring constantly, for 1 minute.

Remove from heat and mix in 10 ml lemon juice and a pinch of salt. Sift out 30g of the jam to use later for the purple cream.

Preheat your oven to 170°C and line a 16 cm round pan with parchment paper for easy removal.

In a bowl, combine 3 eggs, 80g sugar, and 1 teaspoon vanilla. Warm the mixture over a double boiler until it reaches 40°C for better aeration.

Remove from heat and let the residual warmth melt 20g butter and 20g milk in a separate bowl.

Beat the egg mixture for 6 minutes at high speed until fluffy and creamy, then for 1 more minute at low to smooth out air bubbles.

Sift 90g of cake flour in two batches, folding gently with a spatula to maintain the batter’s airiness. Mix a small portion of the batter into the melted butter-milk mixture, then fold it all back into the main batter.

Pour the batter into the prepared pan, tapping it lightly to release any trapped air bubbles. Bake for 40 minutes, allow it to cool in the pan for a few minutes, then transfer to a wire rack to cool completely.

Melt 100g white chocolate with 100g warm heavy cream in the microwave, stirring every 30 seconds to prevent burning.

Gradually incorporate 420g of cold heavy cream, stirring constantly, and chill for 30-45 minutes. Set aside 180g to make the purple cream later.

Slice the cooled sponge cake horizontally into 4 even layers, about 1 cm each. Prepare a simple syrup by dissolving 30g sugar in 75ml water, then lightly brush each layer to keep it moist.

Pipe a border of white cream around the edge of the first layer, fill the center with blueberry jam, and cover with more cream. Repeat this process for the second and third layers.

Place the final cake layer on top, brush with syrup, and coat the top and upper sides with the remaining white cream. Smooth the cream using an offset spatula for a clean, professional finish.

Whip the reserved 180g of chilled cream with 30g of blueberry jam. Add a small amount of purple food coloring for a pastel shade if desired, or leave it natural for a soft look.

Spread the purple cream on the lower sides of the cake, blending upward to create a gradient effect. Pipe decorative swirls around the top edge with a Wilton 4B tip. Slice and enjoy!