Preheat the oven to 350°F (175°C). Grease a standard 5×9-inch loaf pan and set it aside.
In a large bowl or stand mixer, whisk together the keto sweetener, melted butter (or coconut oil), and eggs until combined.
Peel and add the very ripe bananas to the bowl and beat until mostly smooth.
With the mixer on low, add the milk, baking powder, and salt and mix to combine.
Slowly add the flour and vanilla protein powder a little at a time, mixing on low until the batter is smooth. Scrape the bowl as needed.
Fold in the shredded coconut and 1/2 cup of the chocolate chips with a spatula, reserving 2–4 tablespoons of chips for the top.
Pour the batter into the prepared pan and smooth the top. Sprinkle the reserved chocolate chips over the batter.
Bake on the center rack for 40 minutes, then loosely tent the top with foil and bake an additional 15–20 minutes until a toothpick inserted into the center comes out clean.
Run a knife around the edges of the pan, let the loaf cool in the pan for 10–15 minutes, then remove and finish cooling on a rack. Slice once cooled to room temperature for best slices.
