Using softened butter and a room-temperature egg is important to provide the right texture for the dough. To soften butter, set out at room temperature for about 1 hour. Resist the temptation to microwave, which will melt the butter and make it too runny. For the egg (uncracked), place in bowl and top with warm water. Let rest 10 minutes.
Add softened butter to a large mixing bowl and beat with a mixer on high for 30 seconds. Then add cane sugar, vanilla extract, and room temperature egg and beat on high for 1 minute, scraping down sides as needed.
Next add baking powder and sea salt and mix again to combine.
Add almond flour, potato starch, and arrowroot starch and carefully beat on low to combine, switching to a wooden spoon as needed if it becomes difficult to mix. You’re looking for a dough that’s neither crumbly nor too soft, but easy to form in your hand without sticking. If it's too tacky at this point (which we found), add a bit more almond flour, arrowroot, and potato starch a little (~1 Tbsp) at a time and stir until a soft but moldable dough is formed (see photo).
Cover and freeze for 30 minutes or refrigerate overnight. The dough is easier to roll when chilled.
In the meantime, preheat oven to 350 degrees F (176 C) and line 1-2 large baking sheets with parchment paper (the recipe as written yields 48 cookies, and we recommend baking ~12 cookies on a tray at a time).
Once dough is chilled, dust a cutting board or clean surface with arrowroot starch and almond flour (we found the combination to work well to prevent sticking). Then roll into a circle or rectangle about 1/4-inch thick using a rolling pin (add more arrowroot and almond flour as needed to prevent sticking). We found 1/4-inch thick dough to yield fluffy cookies that weren’t too difficult to handle and baked evenly.
Use cookie cutters of choice to stamp cookies, then use a thin spatula (dusted with arrowroot) to carefully transfer them onto the baking sheet. (Alternatively, you can just scoop out 1-1 ½ Tbsp amounts of dough — we like this scoop — roll into balls, and press down slightly to form a disc. Bake as instructed.)
Bake cookies for 8.5 - 10 minutes. They don’t need to be golden brown at all to be baked, and they’re actually more soft and fluffy when pulled out just before browning. NOTE: We had the best success baking cookies 1 tray at a time versus 2 (or more).
Remove from oven and let cool for 5-10 minutes on tray, then transfer to a serving platter or cooling rack, being careful not to stack them until completely cooled.
Optional: To make frosting, add softened dairy-free butter to a mixing bowl and whisk or beat until soft and fluffy — about 1 minute. Then add the vanilla and sifted powdered sugar in 1/2-cup (56 g) increments and mix. Continue adding powdered sugar until you have spreadable frosting (we used about 2 cups powdered sugar // amount as original recipe is written // adjust if altering batch size). For thinner frosting, add dairy-free milk 1 tsp at a time to thin. If it becomes too thin, add more powdered sugar. If it becomes too thick, add more almond milk. Add natural food coloring or powdered dye of choice at this time (or make our matcha variation!). Once completely cooled, frost cookies or leave plain. We decorated with some naturally-dyed sugar sprinkles like these.
Storage: Once cooled, store leftover cookies covered at room temperature or in the refrigerator for 3-4 days or in the freezer up to 1 month.
*We haven’t tested this recipe with coconut oil but suspect it wouldn’t work. Therefore, we highly recommend sticking with vegan butter (Earth Balance brand sticks) or organic dairy butter if not vegan. *If you’d like to cut back on sugar, sub 1/3 cup of the sugar with 1 packet (~1/4 tsp) stevia extract (amount as original recipe is written // adjust if altering batch size). I like Trader Joe’s brand. This will make the cookies softer, so you may need to add more potato starch, almond flour, and/or arrowroot starch to help thicken the dough. *The egg can potentially be substituted for aquafaba (chickpea brine) in this recipe. But we haven’t tested it and can’t guarantee the results. In its place, you can also try subbing 1/4 cup pumpkin purée or 1 egg replacer (amounts as original recipe is written // adjust if altering batch size). But we haven’t tested it with a flax egg or any substitute and can’t guarantee the results. *If not gluten-free, you can sub the almond flour, potato starch, and arrowroot starch with unbleached all-purpose flour, although we haven’t tested it and can’t guarantee the results. *You can make the cookie dough ahead of time and refrigerate up to 2-3 days in advance. Simply let the dough rest at room temperature for 30 minutes before scooping/rolling out and baking. It should be soft and moldable. *Nutrition information is a rough estimate calculated without frosting.