Sift the almond flour and powdered sugar together into a bowl and set aside.

In a separate bowl, whip the egg whites until foamy, then add the granulated sugar a little at a time while continuing to whip until stiff peaks form. Add black gel food coloring and mix until the color is even.

Fold the sifted dry ingredients into the meringue in stages until the batter flows smoothly off the spatula. Transfer to a piping bag and pipe round shells onto a lined baking sheet. Let the shells rest until a skin forms on top.

Bake until the shells lift cleanly from the paper. While the shells cool, heat the heavy cream and pour it over the dark chocolate to make a ganache, stirring until smooth.

Once the shells are cool, pipe ganache onto half of them and sandwich with the remaining shells. Press candy eyes onto the tops to create cat faces.