1. In the bowl of a standing mixer whisk together, eggs, whole cane sugar, vanilla and pinch of salt. Set bowl over pot of simmering water. Whisk constantly until the mixture reaches 160 degrees, about 5 minutes. Beat egg mixture on medium-high with whisk attachment until light and billowy, about 5 minutes. Reduce the speed to medium and add butter one tablespoon at a time. When all of the butter is added it might look curdled, but keep mixing. Turn mixer on high and beat for 1 minute until light and fluffy.

To assemble cookies:

1. Spoon buttercream into a pastry bag with a large tip attached. (If you don’t have a pastry bag, simply spoon the buttercream into a ziploc bag and snip one corner off of the bag.) Pipe about 2 tablespoons buttercream onto half of the cookies. Top the frosted cookies with another cookie to create a sandwich.