This cookie sandwich recipe is filled with a white chocolate butter cream filling.
In a large bowl using an electric mixer beat sugar and butter until light.
Beat in egg and vanilla.
In a small bowl mix together flour, baking powder and salt; add to the creamed mixture just until combined.
Divide the dough in half and gather each pieces into a ball, then flatten.
Wrap in plastic wrap and chill for a minimum of 2 hours.
Set oven to 325 degrees F.
Roll out one disc on a lightly floured surface to about 1/8-inch thickness.
Using a round cookie cutter, cut out the cookies and transfer to an ungreased cookie sheet, leave at least 1 inch between cookies.
Sprinkle a few chocolate chips onto each cookie and lightly pat in.
Repeat with remaining dough.
Bake 10-13 minutes or until golden.
Transfer to wire racks to cool.
White Chocolate Buttercream Filling
Place white chocolate chips in a microwave-safe bowl and heat in 30-second intervals until chips begin to melt.
Stir and repeat until melted and no lumps remain.
Beat butter with an electric mixer on medium speed until fluffy.
Beat in half of the confectioners' sugar, melted chocolate, vanilla and milk until mixture is smooth and creamy.
Slowly beat in remaining confectioners' sugar until smooth and desired consistency is reached.
To make the sandwich cookies, spread or pipe white chocolate butter cream on the inside of one cookie.
Top with another cookie.
Continue making sandwich cookies.
Store cookies in an air-tight container until ready to serve.