Pour the can of condensed milk in a medium saucepan and cook over low heat for about 45 minutes stirring frequently. Be careful not to burn as it sticks to the bottom of the pan.
Add the crushed crackers to a food processor. Pour in the melted butter and pulse until it sticks together and the graham crackers get pulverized. Pour the graham cracker mixture into a 9-inch spring form pan and press with your hands or a 1 cup measurer to evenly distribute on the bottom of the pan. Chill to set for about 15 minutes in the refrigerator.
Pour the dulce de leche over the graham cracker base. Spread evenly. Slice the peeled bananas and arrange over the top covering the entire surface. Whip the cream until firm and spread over the top. Sprinkle top with cinnamon and grated chocolate. Serve.