Sugar Cookie Bars with Vanilla Bean Buttercream

INGREDIENTS

1 cup

. butter (, at room temperature)

2 cups

. granulated sugar

large eggs

egg yolks

1 tbsp

. vanilla extract

4 cups

. all-purpose flour

1 tsp

. baking powder

2 tbsp

. cornstarch

1/2 tsp

. Kosher salt

1 cup

. butter (, at room temperature)

1 tbsp

. vanilla bean paste ((or vanilla extract))

4 cups

powdered sugar

kosher salt

2 tbsp

milk ((enough to make a spreadable consistency))