Preheat the oven to 325°F (160°C). Prepare the springform pan by greasing it with cooking spray or lining the bottom with parchment paper.

In a mixing bowl, combine the graham cracker crumbs, melted butter, and ¼ cup sugar. Mix until the crumbs are evenly coated. Press the mixture firmly into the bottom of the prepared springform pan to form the crust.

In another bowl, beat the softened cream cheese with an electric mixer until smooth and creamy. Gradually add 1 cup sugar and vanilla extract, mixing until well combined.

Add the eggs one at a time, mixing on low speed after each addition until just combined. Be careful not to overmix.

Fold in the sour cream gently with a rubber spatula until just combined.

If using cocoa powder, take about one cup of the cheesecake batter and mix it with the cocoa powder. This will be used for swirling.

Pour half of the plain cheesecake batter over the crust. Then dollop small spoonfuls of the chocolate batter on top and use a knife or skewer to create swirls. Pour the remaining plain cheesecake batter on top and repeat the swirling process.

Arrange the mixed berries on top of the cheesecake, pressing them lightly into the batter.

Bake the cheesecake in the preheated oven for about 60 minutes, or until the edges are set and the center is slightly jiggly.

Turn off the oven and let the cheesecake cool in the oven for 1 hour with the door slightly ajar. This helps prevent cracking.

After it cools, refrigerate the cheesecake for at least 4 hours or overnight for best results before removing it from the springform pan.

Slice, serve, and enjoy your Midnight Berry Bliss Cheesecake!