Butter and flour an 8-inch round cake pan
In a medium bowl, whisk
together the cornmeal, cake flour, minced rosemary, baking powder, and salt.
Using a stand mixer
with a paddle attachment, on low speed beat the butter and vanilla together until combined. Slowly add the powdered sugar. Once the sugar is incorporated increase the speed to high and beat until fluffy, about 3 minutes. Add the egg yolks and eggs
, 1 at a time. Reduce the speed to medium and add the sour cream
. On low speed add the dry ingredients just until incorporated.
Pour the batter
into the prepared cake pan and smooth the surface with a spatula
. Bake in the lower third of the oven until the cake is golden and pulls away from the sides of the pan, about 35 minutes. Transfer the pan to a wire rack and let cool. Transfer the cake from the pan to a serving plate and dust
with powdered sugar