Preheat the oven to 350F and grease a 12-cavity mini donut pan well.
In a large bowl, whisk together the coconut flour, sweetener, protein powder, baking powder, and salt. Whisk in the eggs, butter, and vanilla extract.
Cut the end off a piping bag so that the opening is about ¾ inch wide (you can also use a large ziploc bag with the corner snipped off).
Fill the bag with batter and pipe into the donut wells to about ¾ full. Bake about 15 minutes, or until the mini donuts are golden brown and firm to the touch. Remove and let cool 10 minutes, then transfer to a wire rack to cool completely.
In a heatproof bowl set over a pan of barely simmering water, melt the chocolate and coconut oil together until smooth. Remove from heat.
Dip each donut into the chocolate, tossing to coat. Lift out on a fork and tap firmly on the edge of the bowl to remove excess chocolate. (Note: It may be hard to dip the last few donuts... you can just spread the remaining chocolate on top if you have to!).
Place on a waxed paper lined baking sheet and refrigerate until set.