In a small bowl, combine the flour, coffee grounds, baking powder, and salt. Set aside. Using a stand (or hand) mixer, combine the melted chocolate, sugar, and oil. Add the vanilla extract and eggs one at a time until incorporated. Stir in the flour mixture until just combined. Chill in the fridge for at least two hours.

Once the dough is completely chilled, preheat the oven to 350* F, and line two cookie sheets with parchment paper. Form the cookies into 1-inch balls. Roll the cookie dough balls in the powdered sugar, and place them about two inches apart on the cookie sheets. Bake, checking for doneness around eight or nine minutes. The cookies will be crackled and slightly crispy, but the middles will look like under-cooked brownies. Cool the cookies completely.

Prepare the filling while the cookies are chilling. Place the hazelnuts in a food processor, and process the nuts until they form a butter. This will take about four or five minutes. (*Note: First, it will look like sand, then it will form together in a ball, and then the oils will release and you will have hazelnut butter! If it doesn't look right, I promise, just keep the food processor on, and it will work. Also, make sure to scrape down the sides occasionally with a rubber spatula!)

In a medium bowl, mix together the hazelnut butter, mascarpone, and butter until smooth. Add the powdered sugar, and mix until it's nice and fluffy. Add the vanilla extract, brandy, and a pinch of salt.

Place half of your cookies upside down on a cooling rack. Pipe the filling on the bottoms of the cookies, and sandwich the remaining cookies on top. You will have between 14 and 18 crinkle cookie sandwiches depending on how big your cookies are. Store in an air-tight container in the fridge for up to four days, or freeze them for up to two months.