Preheat the oven to 350 °F (176 C). Melt the butter in the oven as it warms.
Whisk the eggs in a small bowl. Add the milk and butter to the eggs, stir to combine. Set aside.
6 eggs, ½ cup coconut milk, ½ cup butter
In a second bowl, mix all the dry ingredients together. Add the dry mixture to the egg bowl and stir until ingredients are evenly incorporated.
½ cup coconut flour, ½ cup cacao powder, ¼ cup Keto sugar substitute, 2 ½ teaspoon baking powder, 1 teaspoon vanilla extract, ¼ salt
Pour batter into a greased 8 by 8-inch glass baking dish. Bake for 50 minutes, until the center is set and a knife comes out clean after testing the middle.
Remove the cake from the oven and cool. Frost if desired, once cool.