Cream the Butter: In a large mixing bowl, beat the softened butter and granular sweetener together using a hand mixer or stand mixer until the texture is light and fluffy (about 2 minutes).

Add Wet Ingredients: Add the room-temperature egg, vanilla extract, and almond extract to the butter mixture. Beat until fully incorporated and smooth.

Combine Dry Ingredients: In a separate medium bowl, whisk together the almond flour, coconut flour, and sea salt to break up any lumps.

Form the Dough: Slowly add the dry flour mixture into the wet ingredients, mixing on low speed until a cohesive, thick dough forms.

Roll the Dough: Lay out a large sheet of parchment paper on your counter. Place the dough in the center and pat it into a disk. Cover with a second sheet of parchment paper. Use a rolling pin to roll the dough to an even 1/3-inch thickness between the papers.

Cut and Chill: Peel off the top layer of parchment. Use cookie cutters to cut your desired shapes. Carefully lift the cutouts with an offset spatula and place them on a baking sheet lined with a silicone mat or fresh parchment. Place the baking sheet in the freezer for 30 minutes. (This step ensures the cookies hold their sharp edges while baking). Re-roll scraps to make additional cookies.

Preheat: While the cookies chill, preheat your oven to 325°F (165°C).

Bake: Bake the chilled cookies for 12 to 14 minutes, rotating the pan halfway through. They are done when the edges just begin to turn a golden brown.

Cool: Remove from the oven. The cookies will be very soft; let them cool completely on the baking sheet. They will firm up significantly as they reach room temperature.

Prepare Icing: In a clean bowl, whisk together the powdered sweeteners and egg white powder. Gradually whisk in water, one tablespoon at a time, until the icing flows off the whisk in smooth ribbons. Stir in the vanilla. Divide and color as desired, then pipe onto cooled cookies.