Preheat your oven to 210°C (410°F). Line a 6-inch round cake pan or springform pan with parchment paper, pressing it to create rustic folds.

In a large bowl, combine the softened cream cheese, sugar, eggs, heavy cream, and cornstarch.

Use an immersion blender to blend the mixture until it is completely smooth, silky, and free of any lumps.

Pour the batter into the prepared pan and tap it lightly on the counter to release any large air bubbles.

Bake the cheesecake for 25 minutes. It will be deeply golden brown on top, will have puffed up significantly, and the center will still have a pronounced jiggle.

This is perfect—it will set as it cools. Remove it from the oven and let it cool completely in the pan on a wire rack until it reaches room temperature. This is a crucial step before adding the mousse.

While the base cools, prepare the gelatin. Soak the gelatin sheets in a bowl of cold water for 5-10 minutes until soft and pliable. Squeeze out all the excess water.

Add the softened gelatin to 50 g of hot milk in a small heatproof cup, stirring until completely dissolved. Set aside and let it cool slightly until it’s just warm to the touch (not hot).

In a separate bowl, combine the cold heavy cream and blueberry jam. Whip the mixture using a hand mixer or whisk until it thickens to the consistency of thick Greek yogurt—it should hold soft trails. Do not overwhip to stiff peaks.

Pour the warm (not hot) gelatin-milk mixture into the blueberry cream. Fold gently but thoroughly until fully combined and smooth.

Once the Basque cheesecake base is completely at room temperature, gently pour the blueberry mousse over the top.

Carefully tilt the pan or use a small offset spatula to spread it into an even layer. Gently tap the pan on the counter to settle the mousse and remove air bubbles. Refrigerate the cake for at least 4 hours, or preferably overnight, to allow the mousse layer to set completely.

Once fully chilled and set, remove the cake from the pan.

Spread a thin, even layer of blueberry jam over the top of the mousse.

Arrange fresh blueberries in the center or scatter them across the top. Just before serving, dust lightly with powdered sugar. Slice with a hot, clean knife for the neatest slices.