Preheat the oven to 400 degrees F.
Slice the tops of the berries off just below the stem. Cut the tips off (about 1/4-inch), so that the berries will sit upright. Next, use a small spoon or a melon ball scoop to hollow out the strawberries, working from their tops, in order to create a cavity in each one. Stuff some chocolate into the cavity of each strawberry and place them upright in a baking dish. Lightly sprinkle the berries with sugar, if using. Roast the berries until soft and the chocolate is melted, about 10 to 12 minutes.
To serve, place 3 strawberries on a dessert plate in a triangle. If the berries have given off liquid in the baking dish, spoon it over them. Spray a small mound of cream in the center of the berries, and top each berry with a rosette of cream. Sift a little cocoa powder over the plate, and serve!