I keep saying that these cookies can be eaten during Passover because they’re flourless, but they do use powdered sugar which contains cornstarch. Depending on how observant you are, the prohibition against eating rice, beans, and corn has been lifted, so using powdered sugar might be acceptable. If, however, you want to play it safe, use kosher for Passover powdered sugar, or make your own: For the 3 cups of powdered sugar needed for this recipe, grind 2 cups (400 grams) granulated sugar and 1 tablespoon (10 grams) potato starch in an electric coffee or spice grinder until powdery. Measure and use as needed.