In a bowl, combine the graham cracker crumbs, melted butter, and sugar. Mix until the crumbs are evenly coated and the mixture looks like wet sand.

Press the mixture firmly into the bottom of a springform pan, making sure the surface is flat and compact. Place the pan in the refrigerator to chill while you prepare the cheesecake filling.

Preheat the oven to 325°F (160°C).

In a large bowl, beat the softened cream cheese with the sugar and vanilla until smooth and creamy.

Add the eggs one at a time, mixing well after each addition. Do not overmix.

Pour the cheesecake mixture over the chilled crust and smooth the top.

Bake for 25 minutes, or until the cheesecake is just set. Remove from the oven and let cool completely at room temperature.

In a blender or food processor, puree the blueberries with the sugar and lemon juice until completely smooth.

In a small bowl, sprinkle the gelatin over the cold water and let bloom for a few minutes, then heat gently until fully dissolved.

Add the dissolved gelatin to the blueberry mixture and stir well.

In a separate bowl, whip the heavy cream to soft peaks and gently fold into the blueberry mixture.

Pour the blueberry mousse over the cooled cheesecake layer and smooth the top. Refrigerate for at least 4 hours.

In a small saucepan, heat the blueberry jam with the water until smooth and liquid.

Let it cool slightly, then gently pour it over the mousse layer and spread evenly.

Return the cheesecake to the refrigerator to set for about 30 minutes.

Before serving, decorate the cheesecake with whipped cream and fresh blueberries.

Use a sharp knife and wipe the blade between cuts for clean slices.