Preheat the oven to 350 degrees F.
In the bowl of a food processor, combine the almonds, sugar, flour and butter. Pulse lightly until the almonds are ground and the mixture is homogenous. Place the mixture in a mixing bowl.
Using a tablespoon, place small scoops of the mixture on a lightly greased baking sheet, separating each scoop by at least 1-inch on all sides. Use the tips of your fingers to gently flatten the tops of each scoop. Bake for 10 to 12 minutes. Remove from the oven and let cool to room temperature.
Once the cookies have cooled, gently melt the chocolate in the bowl of a bain-marie (a stainless steel bowl fitted over a saucepan of simmering water s that the bowl just touches the water). Remove the melted chocolate from the heat. Carefully pour or spoon a bit of melted chocolate on the tops of half the cookies. If the tops are not flat enough, simply spoon the melted chocolate on the sides of the cookies that were face down during the cooking process. Use the remaining cookie halves to form the other half of the cookie "sandwich," pressing gently so that the chocolate adheres to both sides of the sandwich. Let rest until the chocolate has cooled, holding the cookies together.
Recipe courtesy of Mario Batali