Line 2 large baking sheets with silicone baking sheets or parchment paper. Draw 1 1/2 inch circles over the paper, 1 inch apart.

Process powdered sugar and almond flour in a food processor until finely ground. Sift through a sieve. If you have more that 2 tbsp of the mixture in the sieve, process it and sift again. Set aside.

In the bowl of a stand mixer with the whisk attachment, beat egg whites until frothy. Add sugar 1 tbsp at a time and beat on high for 5 minutes, until stiff peaks form.

Sift the almond meal/sugar mixture over the egg whites. Add gel food coloring. Using a rubber spatula gently fold the dry ingredients into the egg white mixture. Fold until the batter falls into a ribbon from the spatula and takes 20 seconds to spread into the batter.

Fill a pastry bag, fitted with 1/2 inch round tip with batter. Pipe shells onto the circles.

Gently tap the sheets on your work surface, to release any bubbles. Let the cookies stay at room temperature to dry for 30 minutes to 1 hour.

Preheat oven to 325 F. Bake cookies for 10-12 minutes, until set but not browned. If they start to brown, very early, this means your oven is too hot and you need to bring the temperature down.

Transfer baking sheets to a wire rack and let cookies cool down completely.

Peel cookies off the parchment paper (silicone mats) and turn upside down. Be careful not to break them.

Fill cookies with chocolate ganache.

Place chocolate chips in a bowl.

In a small saucepan bring heavy cream to a boil and remove from heat immediately. Pour over chocolate chips. Whisk until combined. Set aside and let it cool for 1 hour before piping into cookies.