Weigh out the ingredients
For the cookies, you'll need butter, flour, powdered sugar, eggs, egg whites, vanilla extract, and salt.
Weight out the ingredients
For the ganache, you'll need heavy cream, chocolate, and mint extract.
In a large bowl, or in the bowl of a stand mixer with the paddle attachment, cream together the butter, powdered sugar, salt, and teaspoon vanilla until light and fluffy.
Cream butter & sugar
Add the egg and egg whites and beat on high speed until fully combined.
Add the flour and mix on low speed until just combined.
Pipe batter onto your cookie template, then place in the fridge for at least 20 minutes. Bake one sheet at a time for 8-10 minutes. Allow them to cool completely on the baking sheet.
Pipe, chill, & bake
In a small saucepan, bring heavy cream to a simmer. Add the chocolate, then place a plate on top for one minute. Stir until smooth. Stir in the mint extract, then transfer to a piping bag and place the piping bag in the fridge until the ganache has firmed up.
Pipe the mint chocolate ganache onto the flat side of one Milano cookie, then sandwich together with another. Repeat until all your cookies are assembled. Enjoy immediately or place in the fridge to crisp up like a store-bought Milano cookie!