Preheat oven to 325F and line 15 standard-sized muffin cups with paper liners (or use silicone muffin cups). You may need to do this in batches if you only have one muffin tin.
In a medium bowl, whisk together the sunflower seed flour, cocoa powder, coconut flour, whey protein, baking powder, instant coffee and salt.
In a large bowl, beat butter with sweetener until well combined. Beat in eggs, vanilla and stevia extract. Beat in half of the sunflower seed flour mixture and then beat in the water. Add remaining sunflower seed flour mixture and beat until fully combined.
Spoon batter into prepared muffin cups to about 3/4 full. Bake 23 to 25 minutes or until cupcakes are puffed, slightly cracked on the top and firm to the touch.
Remove and let cool completely.
In a glass measuring cup, combine cream and water and mix well.
In a large bowl, beat melted butter with cocoa powder until well combined. Add 1 cup of the powdered sweetener and stir without turning on your beaters first (otherwise it will create a huge cloud of dust all over!). Then beat in the sweetener until smooth.
Add about half of the cream/water mixture and beat together, then add remaining powdered Swerve. Add cream/water mixture a little at a time until desired consistency is achieved. Beat in vanilla extract.
Pipe or spread frosting on cooled cupcakes and serve.
Serves 15. Each serving has 8.3 g of carbs and 4.08 g of fiber. Total NET CARBS = 4.22 g.Food energy: 306kcal
Saturated fatty acids: 13.28g
Total fat: 27.47g
Calories from fat: 247
Total dietary fiber: 4.08g