Position an oven rack in the center of the oven and preheat to 325 degrees F. Coat a 9-inch springform pan with cooking spray. Wrap the bottom and sides of the pan with a large piece of foil and place the pan on a rimmed baking sheet.

Put the graham crackers into a food processor and pulse until fine. Add the butter and process until the crumbs are moistened. Press the crumbs into the bottom and about 1/2 inch up the sides of the prepared pan. Bake until the crust is slightly dry in appearance and fragrant, about 5 minutes. Cool completely.

Cut two thin strips from the lime and form into tight curls, zest the remainder, set both aside.

Combine the yogurt, cream cheese, eggs, sugar, flour, vanilla, coconut extract, lime zest and salt in a food processor and process until well blended and smooth. Pour over the prepared crust and bake until the center is just set, 40 to 50 minutes. Let cool completely on a wire rack, then cover and chill in the refrigerator for at least 3 hours or overnight.

Put 2 cups of the raspberries and the juice in a medium saucepan and bring to a boil. Break half the dark chocolate bar into small pieces and add slowly to the mixture, stirring constantly until melted. Reduce heat to low and cook for 5 minutes, then remove from heat.

Sprinkle the gelatin over 1 tablespoon water in a small bowl and let stand 5 minutes. Stir the dissolved gelatin into the hot raspberry-chocolate mixture until combined. Transfer the mixture to a medium bowl, cover and chill until thickened, about 3 hours.

After chilling the cheesecake, remove the springform ring. Slice and serve, topped with the raspberry-chocolate sauce. If the sauce is too thick, rewarm it in the microwave for 20 seconds at a time before spooning over the cheesecake.

Decorate with remaining chocolate, remaining raspberries and lime curls.