Cinnamon Bun Base:
Preheat your oven to 350°F (175°C) and grease the bottom of a 9-inch springform pan.
In a large bowl, whisk together the flour, baking powder, and salt.
Add the butter to the dry ingredients and beat on medium speed until just blended. Avoid overmixing.
Beat in the milk until combined, then stir in the brown sugar, granulated sugar, and cinnamon until well mixed.
Press the mixture evenly into the greased springform pan. Place the pan on a baking sheet to catch any drips.
Bake for 23-25 minutes until lightly golden. Remove from oven and set aside.
Cheesecake Layer:
Reduce oven temperature to 325°F (163°C).
In a large bowl, beat the softened cream cheese and granulated sugar together until smooth and creamy.
Add the eggs one at a time, beating well after each addition. Then mix in the sour cream, vanilla extract, light brown sugar, cinnamon, and all-purpose flour until fully combined.
Pour the cheesecake batter over the pre-baked cinnamon bun base, smoothing the top with a spatula.
Bake for 80-90 minutes until the top is golden brown and the center is set (no longer jiggly).
Allow the cheesecake to cool on a wire rack for 1 hour, then refrigerate for at least 4 hours or overnight before icing.
Icing:
In a medium bowl, beat together the softened cream cheese and butter until smooth.
Add the brown sugar, granulated sugar, cinnamon, and confectioners’ sugar, beating until well combined.
Spread the icing evenly over the cooled cheesecake.
Store any leftovers in the refrigerator.