1Preheat the oven to 350 ° F
2Beat the sugar and butter together, using either a handheld mixer or a stand mixer fitted with this whisk attachment. Add the eggs, one by one, and whisk until the mixture is creamy. In a large bowl combine the flour, salt and baking powder. Gradually add the dry ingredients to the egg mixture, beating well between each addition. Add the condensed milk, vanilla and water. Mix at low speed to get a smooth batter.
3Grease your pan with melted butter place 3 tablespoons of batter, spread with the back of the spoon . Cook 8 to 9 minutes (the edge of the cake turns brown but not the center). Take your pan from the oven and turn out onto a wire rack to cool. Repeat baking another cake, buttering well each time. You need to bake 10 cakes with your batter. If, when unmolding one of the cakes, it gets a little damaged, don't panic because once the cakes are covered with icing no one will notice anything).
4Start making the glaze while the first cake is baking. In a saucepan, pour the milk and add the butter, melt the butter over low heat to obtain a homogeneous mixture. Add the cocoa gradually while whisking the mixture (to avoid lumps) and cook over low heat for 10 minutes (the mixture shouldn't boil). Off the heat, gradually add the powdered sugar. Turn the heat back on to reduce over low heat until the mixture thickens slightly and coats the back of a spoon. Let it cool.
5When all the cakes are cooked and cooled. Place the first cake on a wire rack, spread glaze to cover the surface (2-3 tablespoons), add some chopped M&M's (in very small pieces). Cover with a second cake that you will also glaze and so on until the tenth cake. Glaze the entire cake. In order to do it I place my wire rack with the cake over a plastic tray or a baking sheet, so that I can pour the glaze over the cake and save the excess to reuse on the cake. Decorate the surface of your cake with M&M'S. Store in the refrigerator at least for 4 hours before transferring to your dish to serve (it must be very cold so it does not break).