Pre-heat oven to 350°. Grease and flour a 9 inch bundt pan.
In a large bowl beat on medium speed eggs and sugar until light and creamy for 5 minutes, then add the mascarpone and beat, then add the melted (cooled) butter and vanilla, combine well.
In a medium bowl whisk together the flour, baking powder and salt.
Add the flour mixture alternately with the milk to the creamed mixture. Beat until smooth.
Pour 2/3 of the mixture into prepared pan the remaining 1/3 stir in the cocoa and pour over the top of the batter, swirl slightly with the tip of a knife, bake for approximately 40-50 minutes, check for doneness with a toothpick. (make take longer, depends on the oven). Cool completely before topping with glaze. Enjoy!
In a small pot heat the sweetened condensed milk and the chocolate, stir until smooth, remove from heat and add the vanilla, combine, let cool slightly before pouring over cake.