Line a fine-mesh strainer with a double layer of wet cheesecloth. Put the ricotta in a strainer and set it over a bowl. Fold the cheesecloth over the top of the ricotta. Refrigerate for at least 4 hours, up to overnight. Discard the whey which collects in the bowl.
In a stand mixer outfitted with the paddle attachment, beat the confectioners' sugar, cinnamon, vanilla and chocolate chips into the thickened ricotta on low speed until well combined. Transfer to a bowl, cover with plastic wrap and chill until needed.
Preheat the oven to 325°F Grease and flour two 9" cake pans.
Sift together the flour, baking powder and salt; set aside.
Separate the eggs and set the whites aside. In the bowl of the stand mixer, beat the yolks until very thick and pale yellow, about 4 minutes. Gradually add the cold water, then the sugar. Beat well until sugar is dissolved. Add vanilla extract, then slowly add the sifted flour.
Beat the egg whites with the cream of tartar until stiff peaks form. Fold the whites into the batter carefully. Divide batter evenly between the prepared cake pans.
Bake in preheated oven 25 minutes or until a cake tester comes out clean. Cool in pans 10 minutes, then turn out onto a rack and cool completely.
Place the remaining sugar and water in a small saucepan. Bring to a boil over medium heat, then simmer until sugar is completely dissolved. Cool to room temperature, then stir in the rum.
Split the cake layers horizontally, to make 4 thin layers. Place one layer on a cake board or plate and drizzle or brush with rum syrup. Top with 1 to 1 1/2 cups of the filling. Place another cake layer on top, and repeat until all four layers have been placed.
In a microwave-safe bowl, sprinkle gelatin over cold water and let stand five minutes. Microwave in 10 second intervals until gelatin is just dissolved, stirring after each interval. If it boils, throw it out and start over.
Whip cream with confectioners' sugar until soft peaks form. Add melted gelatin and whip until stiff peaks form.
Spread frosting over top and sides of cake. Press sliced almonds all around the sides of the cake.