Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or a 10-inch pizza pan.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.

Beat in the eggs one at a time, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.

Press the cookie dough evenly into the prepared cake pan.

Bake for 20-25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.

In a medium bowl, beat the softened cream cheese and butter until smooth.

Gradually add the powdered sugar, beating until well combined. Stir in the vanilla extract.

Add milk, one tablespoon at a time, until the frosting reaches your desired spreading consistency.

Once the cookie cake is completely cool, spread the frosting evenly over the top.

Decorate with sprinkles, if desired.

Slice and serve.