Preheat your oven to 325°F (160°C). Grease a 9-inch springform pan and set aside.
In a mixing bowl, combine the graham cracker crumbs, 1/4 cup sugar, and melted butter. Press the mixture evenly into the bottom of the prepared pan to form the crust.
In a separate bowl, beat the cream cheese, 1 cup sugar, and vanilla extract until smooth and creamy.
Add the eggs one at a time, mixing well after each addition.
Gently fold in the fresh raspberries.
Pour the cream cheese mixture over the prepared crust in the pan.
In a small saucepan, heat the raspberry jam over low heat until melted and smooth. Drizzle the melted jam over the top of the cheesecake batter.
Use a knife or toothpick to gently swirl the raspberry jam into the cheesecake batter, creating a marbled effect.
Bake the cheesecake in the preheated oven for 45-50 minutes, or until the center is almost set.
Remove the cheesecake from the oven and allow it to cool completely at room temperature. Once cooled, refrigerate for at least 4 hours or overnight before serving.
Garnish with fresh raspberries before serving, if desired.