Preheat the oven to 350 F. Combine the dry ingredients, including the almond flour, coconut flour, sweetener, xanthan, baking powder, and sea salt. It is easiest to use a whisk for this step.
Next, add in the eggs, both extracts, almond milk, both zests, and both juices. Mix well to combine. You can use a wooden spoon or a spatula for this step—Line a 12-count cupcake tin with liners.
Use a cookie scoop to portion the batter into each cupcake liner. A cookie scoop will allow for a rounded top on each batter mound for an excellent shape after baking. Bake 20-25 minutes or until a toothpick inserted inside the center of a butter cake comes out clean.
While the cupcakes are baking, combine the remaining ingredients and stir with a small spatula. The glaze should be smooth and lump-free. Allow the butter cakes to cool slightly before removing them from the cupcake tin to a cooling rack. Once cooled, drizzle each with the glaze and top with any remaining zest.