Preheat a waffle maker to high heat.
In a medium mixing bowl, combine the almond flour, coconut flour, sweetener, baking powder, and salt, then set aside.
In another mixing bowl, mix together the mascarpone, vanilla extract (optional), and melted butter until fully combined, then add two eggs and mix well.
Combine the wet and dry ingredients together. Add the water and whisk again.
Pour the batter into the waffle maker and cook until golden. This will take from 2-5 minutes per waffle, depending on your waffle maker. Repeat with the rest of the butter.
Serve with freshly whipped cream and berries of your choice.