Chocolate Macarons: Have ready three baking sheets (make sure they have flat bottoms (no warping)) lined with parchment paper. To make all the Macarons the same size, I like to make a template. Take a piece of parchment paper and draw 20 - 1 1/2 inch (4 cm) circles, spacing the circles about 2 inches (5 cm) apart. Place the template under your parchment paper so you can use it as a guide.

Place the ground almonds, confectioners sugar, and cocoa powder in your food processor and process until they are mixed together (about 30 seconds). Then sift the mixture to remove any lumps.

In the bowl of your electric mixer, fitted with the whisk attachment (can use a hand mixer), beat the egg whites and cream of tartar on medium speed until foamy. Gradually add the sugar, and continue to beat, on medium-high speed, until the meringue just holds stiff peaks (when you slowly raise the whisk the meringue stands straight up (no drooping)). Then, in three additions, sift the ground almond mixture over the meringue. When folding, cut through the meringue and then fold up and over, making sure to scrape the bottom and sides of the bowl. Once the almond mixture is completely folded (called macaronage) into the meringue (the batter will fall back into the bowl in a thick ribbon) it is time to pipe the Macarons.

Fill a pastry bag, fitted with about a 1/2 inch (1 cm) plain tip, with about half the batter. Pipe about 1 1/2 inch (4 cm) rounds onto the parchment paper, using the template as a guide. Then carefully remove the template and gently tap the baking sheet on the counter to break any air bubbles (can also break air bubbles with the end of a toothpick). Let the Macarons sit at room temperature for about 30-60 minutes (depending on the temperature and humidity of your kitchen) or until the tops of the Macarons are no longer tacky when lightly touched.

Meanwhile, preheat your oven to 325 degree F (160 degree C) with the oven racks in the top and bottom third of the oven. Bake the cookies (two sheets at a time) for about 14 - 16 minutes, rotating the pans top to bottom, front to back, about halfway through baking. The Macarons are done when they just barely separate from the parchment paper. Remove from oven and let the Macarons cool completely on the baking sheet placed on a wire rack. To assemble the Macarons, take two cookies and sandwich them together with chocolate ganache. While you can serve the Macarons the day they are made, these cookies really need to mature for a day or two in the refrigerator. Bring to room temperature before serving.

Chocolate Ganache: Place the chopped chocolate in a  heatproof bowl. Heat the cream and butter in a small saucepan over medium heat (or in the microwave). Bring just to a boil. Immediately pour the hot cream over the chocolate and allow to stand for a few minutes. Stir gently until smooth. If desired, add the liqueur. Let sit at room temperature until thick and of piping consistency. (This can take a few hours.) You can make the ganache the day before. Just cover and store at room temperature.

Makes about 30 Macarons.