Prepare the sugar cookie base by mixing sugar cookie mix, cream cheese, granulated sugar, and vanilla extract until smooth. Spread evenly in a greased 9-inch springform pan.
Make the cheesecake filling by whisking together sour cream, flour, baking powder, and salt. Gradually add to the cream cheese base and stir until smooth.
Pour the cheesecake filling over the sugar cookie base and smooth the top. Tap the pan to remove air bubbles.
Bake in a preheated oven at 325°F for 30-35 minutes until edges are set and center is slightly jiggly. Turn off the oven and let it cool inside for 30 minutes.
Cool to room temperature, then refrigerate for at least 4 hours or overnight before serving. Top with sprinkles if desired.