Line a baking sheet with parchment paper and set aside. In a small bowl, whisk together the cocoa powder, collagen and maple sugar. Whisk in the warm melted cacao butter and vanilla until smooth. Pour onto the lined baking sheet and spread evenly and thinly using an offset spatula. Scatter some raspberries over it and refrigerate until firm, at least 2 hours or up to overnight. Peel off to eat, tearing into pieces to make servings.