Preheat the oven to 350F and grease two 4-inch springform pans or 4-inch diameter ramekins. In a medium bowl, whisk together the coconut flour, Swerve, cocoa powder, baking powder, and salt. Stir in the egg, melted butter, and vanilla extract. Add 2 tablespoons of the coffee or water until well combined. If the batter is very thick, add the additional water. Divide the batter between the two pans and spread to the edges. Bake 15 to 18 minutes, until they have risen and are firm to the touch. Remove and let cool in the pans, then run a sharp knife around the pan sides. If using springform pans, just release the pan sides to remove the cakes. In a medium bowl, beat the cream with the sweetener, collagen, and vanilla until it holds stiff peaks. Reserve a tablespoon of the mixture for the top of the cake. Place one cake layer on a small plate and spread with the remaining filling. Place the other cake layer on top of the filling. In a small microwave-safe bowl, heat the cream on high until it bubbles. Quickly add the chopped chocolate and let sit for a few minutes to melt. Add the powdered sweetener and vanilla extract and whisk until smooth. Let cool a few minutes to thicken and then pour over the top of the cake, allowing it to drip down the sides. Spread over the sides if desired. Refrigerate 30 minutes to set, then pipe or dollop the reserved cream filling on top.