Preheat your oven to 350°F (175°C). In a bowl, combine graham cracker crumbs with melted unsalted butter until well mixed. Transfer the mixture to a 9-inch springform pan and press it firmly into the bottom to create an even crust. Bake for 8-10 minutes, until golden brown and fragrant. Remove from the oven and set aside to cool while you prepare the filling.

In a large mixing bowl, beat softened cream cheese with an electric mixer on medium speed until smooth and creamy, about 2 minutes. Gradually add sour cream, granulated sugar, and vanilla extract, mixing until fully combined and smooth. Add eggs one at a time, mixing on low speed just until incorporated to avoid overmixing; the cheesecake filling should be silky and lump-free.

In a saucepan over medium heat, combine fresh strawberries and a touch of granulated sugar. Cook for about 5-7 minutes, stirring occasionally, until the strawberries break down and the mixture becomes syrupy. Remove from heat and let cool completely.

Pour half of the creamy cheesecake filling into the cooled crust, smoothing it out with a spatula. Drizzle half of the prepared strawberry sauce over the top, then use a knife or skewer to create swirls through the batter. Add the remaining cheesecake filling and top with the rest of the strawberry sauce, swirling gently once more.

Prepare a water bath by placing a larger roasting pan filled with hot water on the lower oven rack. Place the springform pan with the cheesecake into the oven on the middle rack. Bake at 325°F (160°C) for 50-60 minutes, or until the edges are set but the center still has a slight jiggle.

Once baked, turn off the oven and leave the cheesecake inside with the door slightly ajar. Allow it to cool gradually for about 1 hour, then let it cool to room temperature before transferring it to the refrigerator for at least 6 hours (or overnight) before serving.