Preheat the oven to 350℉. Line a 9”x13” pan with parchment paper. Set aside.
In a medium mixing bowl, whisk cake flour, cornstarch, baking powder and salt together. Set aside.
In a large mixing bowl, cream butter and sugar together with a hand mixer.
Add egg, vanilla and coconut extracts and mix until well blended.
Add in sour cream and beat until fully combined.
Incorporate dry ingredients, mix until just combined.
Drop batter by large spoonfuls into the prepared dish. Batter will be very thick. Spread batter evenly for uniform baking.
Bake for 18-20 minutes or until the edges are slightly browned. Don’t overbake.
Cool completely before frosting.
For Frosting:
Beat softened butter until creamy, about 1 minute.
Add powdered sugar, vanilla and coconut extracts, salt, and 2 Tablespoons of heavy cream.
Beat until desired consistency is attained, thinning with more heavy cream if needed.
Spread onto bars and top with shredded coconut.
Notes
Make sure the ingredients called for are at room temperature.
This recipe can be halved and made in a 9"x9" baking dish.
You can toast your coconut for the topping: line a baking sheet with parchment paper, add coconut in a single layer and bake at 350℉, stirring regularly for about 8-10 minutes.
These can be frozen, see tips above on how to do that.