Preheat your oven to 350°F (175°C). In a large mixing bowl, cream together the softened unsalted butter and granulated sugar until light and fluffy, about 3-5 minutes. Beat in the egg and vanilla extract. In another bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually mix the dry ingredients into the butter mixture until well combined. Press the dough evenly into the bottom of a 9-inch springform pan and bake for 10-12 minutes until the edges are golden.

While the crust is cooling, prepare the cheesecake filling. In a large bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth, about 2 minutes. Gradually add granulated sugar and vanilla, mixing until well incorporated. Add in the eggs one at a time, blending on low speed after each addition. If using, stir in the optional sour cream until the mixture is creamy and lump-free.

Once the crust has cooled slightly, pour the cheesecake filling over the crust and smooth the top with a spatula. Tap the pan on the counter to release any air bubbles.

Reduce the oven temperature to 325°F (163°C) and bake the cheesecake for 40-50 minutes, until the edges are set but the center has a slight jiggle. Cover the edges with aluminum foil if they start browning too quickly.

Remove from the oven and let it cool at room temperature for about 30 minutes. Refrigerate for at least 3-4 hours or overnight before serving.

Carefully remove the cheesecake from the springform pan. Garnish with whipped cream, fresh berries, and sugar sprinkles. Slice and enjoy!