Peel the eggplants and cut lengthwise. Boil in 4 cups of water, together with 1/4 cup sugar and a stick of cinnamon, until soft. In a bowl, whisk together the ricotta and remaining sugar. Add in the chocolate shavings. Arrange two eggplant slices, forming a cross, in each of 4 aluminum molds. Add a heaping tbsp of ricotta to the middle of each cross and fold over forming little tarts. Place the molds in the refrigerator and let cool for an hour. Melt the dark chocolate in a bain marie. Remove the tarts from the molds and place on individual plates. Pour the hot, melted chocolate on top.