Preheat the oven to 350 degrees F. Spray a 9-inch square cake pan with nonstick spray or line with parchment paper and set aside.
In a large bowl, combine coconut flour, baking soda, and salt. Whisk well and set aside.
In another bowl, add the cooled butter, eggs, erythritol, stevia, vanilla, and coconut milk. Whisk until fully combined.
Pour the wet ingredients into the bowl with the dry ingredients and whisk well until well- combined. Pour batter into the prepared pan, smoothing the top with a spatula.
Bake for 26 to 30 minutes, until a toothpick inserted into center of the cake comes out clean, the cake is deeply golden at the edges, and the center springs back lightly when touched.
Place the pan on a wire rack and let cool in the pan completely.
Coconut Whipped Cream
While the cake cools, prepare the frosting.
When ready to whip, scrape chilled coconut cream into a medium bowl and discard the water. Use a hand mixer to beat for 30 seconds until creamy, then add vanilla and stevia and whip 1 minute until creamy and smooth. Taste and adjust sweetness as needed.
Spread in an even layer on top of cooled cake immediately. Keep leftover cream covered in refrigerator.
Slice into 9 and serve. Best stored in an air tight container in the fridge up to one week.