Preheat your oven to 350°F (175°C). Cream together unsalted butter and granulated sugar until light and fluffy. Add egg and vanilla extract, mixing until combined.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually blend dry ingredients into the wet mixture to form a dough. Press dough into springform pan and bake for 10-12 minutes. Allow to cool slightly.

Beat cream cheese in a bowl until smooth. Gradually add granulated sugar and vanilla extract. Add eggs one at a time, mixing well after each addition. Mix in flour and sour cream until creamy.

Pour the cream cheese filling over the cooled crust, smoothing the top. Tap the pan lightly on the countertop to remove air bubbles.

Lower oven temperature to 325°F (163°C) and bake for 40-50 minutes until edges are set but center is slightly jiggly. Cover edges with aluminum foil if browning too much.

Cool gradually by cracking the oven door for about 30 minutes. Then chill in the refrigerator for at least 3-4 hours or overnight.

Remove from the springform pan and garnish with whipped cream, sprinkles, and fresh berries before serving.