Orange Creamsicle Cake:
Preheat oven to 350°. Prepare three 6-inch cake pans with butter flour and parchment paper. Set aside.
Sift together the flour, baking powder, baking soda, and salt. Set aside.
In a separate bowl, stir together the sour cream, milk, and vanilla. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat the butter until smooth. Add in the sugar and the zest. Mix on medium for about 3 to 5 minutes until fluffy and pale in color. Turn the mixer to medium low and add in a yolks, one at a time. Stop mixer and scrape down the sides and bottom of the bowl.
With the mixer on low, add in half of the flour mixture. Add in sour cream mixture and mix until combined. Stop mixer and scrape down the bowl. Turn mixture back to low and add remaining flour mixture. Mix on medium- low for no more than 20-30 seconds once the last traces of flour are combined.
Evenly distribute between the three prepared pan’s bake for about 24 to 26 minutes or until a toothpick inserted in the center of the cakes comes out clean. Let cool for 10 to 15 minutes before removing cakes from their pan.
For the Orange Simple Syrup:
Placed all of the ingredients in a medium sauce pan. Heat over medium height and bring to a boil. Reduce heat and simmer for about 8 to 10 minutes. Remove from the heat and let cool before use.
For the Orange Cream Filling:
In the bowl of electric mixer fitted with the paddle attachment, beat butter until smooth. With the mixer on low, gradually add in the confectioner’s sugar until combined. Add in the mascarpone, orange zest and orange juice and mix on medium-low until smooth. Be sure not to overmix the filling once the mascarpone has been added.