Preheat the Oven: Start by preheating your oven to 350°F (175°C). Grease a 6-cavity donut pan with cooking spray or coconut oil and set aside.
Combine Dry Ingredients: In a medium bowl, whisk together the almond flour, coconut flour, granulated erythritol, unsweetened cocoa powder, baking powder, and salt until well combined.
Mix Wet Ingredients: In a separate bowl, mix the melted butter, eggs, vanilla extract, and almond milk until smooth.
Combine Mixtures: Pour the wet ingredients into the dry ingredients, stirring until just combined. Avoid overmixing to ensure your donuts are tender.
Fill Donut Pan: Spoon the batter into the greased donut pan, filling each cavity about 3/4 full. You can also pipe the batter in using a piping bag or a ziplock bag with the corner cut off for a cleaner approach.
Bake: Place the donut pan in the oven and bake for approximately 15 minutes or until a toothpick comes out clean when inserted into a donut.
Cool: Remove the pan from the oven and let the donuts cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely.
Make the Glaze: While the donuts are cooling, create the chocolate glaze by melting the sugar-free chocolate chips and coconut oil together. You can do this using a double boiler or by microwaving in 30-second intervals, stirring between each, until smooth.
Glaze Donuts: Dip the top of each cooled donut into the chocolate glaze, then return to the wire rack. If desired, sprinkle with optional toppings such as chopped nuts or keto-friendly sprinkles.
Set: Allow the glaze to set at room temperature, or place the donuts in the fridge for a faster setting glaze.