Position the racks in the lower and upper thirds of the oven. Put a small roasting pan on the lower rack and fill about 1/3 full of water. Preheat the oven to 160°C. Lightly coat a 9-inch springform tin with cooking spray and wrap the outside bottom of the tin with aluminum foil to prevent any leaks.
Base: Mix the biscuit crumbs, sugar, water, and melted butter in a medium bowl until moistened. Press into the bottom of the prepared pan. Freeze until firm, about 15 minutes, while preparing the filling.
Filling: Put the chocolate in a microwave-safe bowl. Microwave on medium power until soft and melted, about 1 minute, depending on the power of your oven. Stir until smooth. Puree the cottage cheese in the bowl of a food processor until smooth. Add the cream cheese, sugar, cocoa, and flour and continue to puree, scraping down the sides of the bowl, until smooth. Add the egg, egg whites, espresso, and vanilla and puree until incorporated. Add the melted chocolate and pulse until just combined. Pour over the prepared base.
Put the tin on the upper rack in the oven and bake until just set and the center jiggles slightly, about 50 to 55 minutes. Turn off the oven and let stand in the oven for 1 hour. Remove the cheesecake to a cooling rack and run a knife around the edge of the pan.
Let stand at room temperature until cooled, about 2 hours, and then refrigerate until well chilled, 8 hours or overnight. Let stand at room temperature for about 1 hour before serving. For easier serving, slice with a clean hot knife, wiped clean after each slice. Serve each slice with a few fresh raspberries and a sprig of mint.