4 eggs
1 cup white sugar
1 cup milk
1/2 cup butter
2 teaspoons vanilla extract
1 (8 ounce) container vanilla sweetened condensed milk
1 (9 inch) pan
1 (1 ounce) square unsweetened chocolate, chopped
Preheat oven to 350 degrees F (175 degrees C). Grease two baking sheets or line with parchment paper and oil them with non-stick baking sheets.
In a medium saucepan over medium heat, combine eggs and sugar, stir until completely combined. Set aside.
In a large bowl, cream together the butter and vanilla. Whisk in the flour, one teaspoon at a time, beating well after each addition. Stir in the remaining flour, one teaspoon at a time, until well mixed. Finally, stir in the chocolate mixture, one tablespoon at a time, beating well after each addition. Stir in the dry ingredients until just combined. Spread evenly into prepared pan.
Bake in the preheated oven for 15 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.