Whisk together coconut flour, baking powder, and ⅓ cup of granulated sweetener in a medium bowl.
In a separate medium bowl, add the eggs, heavy cream, oil, and vanilla. Whisk well to combine.
Add the wet ingredients to the dry ingredients and mix until just combined. Don’t overmix.
Spray a 12-cup muffin pan with cooking spray or line it with muffin cups. Add about 2 tablespoons of batter to the bottom of each muffin cup.
In a small bowl, combine the cinnamon and ¼ cup of granulated sweetener.
Top each partially filled muffin cup with 1 teaspoon of the cinnamon sugar, then divide the rest of the batter evenly among the muffins, adding the batter on top of the cinnamon sugar.
Divide the rest of the cinnamon sugar between the muffins, sprinkling it over the tops.
Bake at 375°F for about 25 minutes or until a toothpick comes out clean.
To make the icing, mix the powdered sugar substitute with vanilla and 3 tablespoons of cream until the consistency is smooth and can easily be drizzled on top of the muffins. If necessary, add 1 tablespoon of cream at a time until you reach the desired consistency to drizzle, but not pour.
Top the cooled muffins with a drizzle of the icing and enjoy!