Preheat your oven to 350°F (175°C). In a large mixing bowl, cream together softened unsalted butter and granulated sugar until light and fluffy, about 3-4 minutes.

Beat in one egg and a splash of vanilla extract. In a separate bowl, combine all-purpose flour, baking powder, and salt.

Gradually mix the dry ingredients into the wet, forming a dough. Press this mixture firmly into the bottom of a 9-inch springform pan and bake for 10-12 minutes, until just golden.

While the crust cools slightly, gather another mixing bowl to beat the softened cream cheese until smooth, around 2-3 minutes.

Gradually add granulated sugar and vanilla extract, mixing until well combined. Add eggs one at a time while mixing on low speed, ensuring a creamy consistency.

If using, gently fold in sour cream and a bit of flour until the mixture is smooth and uniform.

Once your sugar cookie crust has cooled, pour the creamy cheesecake filling over it, using a spatula to smooth out the top.

Lower the oven temperature to 325°F (163°C) and place the springform pan in the oven. Bake for about 40-50 minutes, until the edges are set, but the center remains slightly jiggly.

After baking, remove the cheesecake from the oven and allow it to cool at room temperature for about 30 minutes.

Once it's slightly cooled, refrigerate it for at least 3-4 hours, or preferably overnight.

When ready to serve, carefully remove the cheesecake from the springform pan. Garnish with whipped cream, a sprinkle of sugar, and fresh berries.

Slice your Sugar Cookie Cheesecake, serving it chilled and savoring the delightful combination of flavors.