In a mixing bowl, combine graham cracker crumbs, melted butter, and sugar until well mixed. Pour this mixture into a 9-inch springform pan and press it firmly into the bottom and slightly up the sides to form an even crust. Chill this crust in the refrigerator for about 15 minutes to set while you prepare the filling.

In a large bowl, beat together room-temperature cream cheese, powdered sugar, sour cream, lemon juice, and vanilla extract until the mixture is smooth and creamy, about 3–5 minutes. Be careful to avoid overmixing to maintain a light texture.

In a separate bowl, whip the heavy cream until soft peaks form, which should take about 3–4 minutes with an electric mixer. Gently fold the whipped cream and 1 cup of fresh blueberries into the cream cheese mixture.

Pour the blueberry filling over the chilled crust in the springform pan, smoothing the top with a spatula for a neat finish. Cover the cheesecake with plastic wrap and refrigerate for at least 2 hours.

Before serving, remove the cheesecake from the refrigerator and gently run a knife around the edges to release it from the pan. Top with additional fresh blueberries and an optional drizzle of warmed blueberry jam, then slice and enjoy.