Preheat your oven to 325°F (163°C). Wrap the bottom of a 9-inch springform pan with aluminum foil and lightly grease the sides.
In a bowl, combine graham cracker crumbs, melted butter, and granulated sugar. Mix until well combined, then press firmly into the bottom of the pan to form an even crust. Bake for 10 minutes and set aside to cool.
In a small bowl, dissolve 2 tablespoons instant espresso powder in 2 tablespoons hot water. Let cool slightly.
In a large bowl, beat softened cream cheese until smooth and creamy. Add granulated sugar and vanilla extract; mix until well blended.
Add eggs one at a time, mixing on low speed after each just until combined. Do not overmix.
Mix in flour and sour cream, then stir in dissolved espresso mixture until batter is smooth and uniform.
Pour filling over the crust and smooth the top with a spatula. Place the pan on a baking sheet.
Bake for 50–60 minutes until the center is almost set but still slightly jiggly. Turn off the oven, crack open the door, and let the cheesecake cool in the oven for 1 hour.
Remove from oven and let cool completely at room temperature, then refrigerate for at least 4 hours or overnight.
To make the optional topping, beat 1/2 cup heavy cream with 2 tablespoons powdered sugar and 1 teaspoon instant espresso powder until soft peaks form. Serve cheesecake with a dollop of coffee whipped cream on top.