Place the all-purpose flour, hazelnut flour, brown sugar, granulated sugar and kosher salt in the bowl of a food processor. Process the dry ingredients for about 20 seconds.

Cube the butter into 1-inch cubes and add them to the food processor. Pulse about 30 times until the dough resembles breadcrumbs. Don’t let the dough form a call.

Pour the dough onto a lightly floured Silpat and knead the dough into a ball. Roll the dough out to 1/4-inch thickness and cut out 2.5-inch circles. Line a baking sheet or flat board with parchment paper and place the cookies on the paper. Prick each cookie with a fork. Chill in the refrigerator for at least 30 minutes or up to 2 days.

Preheat the oven to 300°F. Line a half baking sheet with parchment paper. Place the cookies on the sheet 2 inches apart and bake for 20 minutes.

Remove the cookies from the oven and let them cool for 5 minutes before moving them to a cooling rack.

Chop the chocolate into 1/2-inch or smaller pieces. Place the chopped chocolate in a medium-sized bowl. Heat the cream on medium heat until it just begins to bubble. Be careful not to let the cream bubble over.

Remove the cream from the heat and add the instant coffee or espresso to the cream and whisk to combine. Pour the hot cream over the chopped chocolate. Let it sit for 1 minute. Whisk the cream and chocolate until the mixture is smooth.

Let the chocolate cool until it is 77°F. Add a decorating tip to an 18-inch pastry bag. I used Ateco #808. Pipe a single layer of milk chocolate ganache on one cookie and place a second cookie on top.

The cookies can sit at room temperature for two days. Refrigerate the cookies for up to one week. As the cookies sit with the ganache, the cookies will get soft.