In a large bowl mix together the mascarpone, sugar, beaten eggs and vanilla.
Fold in the whipped cream. Set this mixture aside.
In a shallow dish stir together the Porter beer and the brewed coffee, Dip the ladyfingers cookies into the coffee mixture (note: if you are using regular non-Italian ladyfingers make it a quick dunk).
Don't let the ladyfingers get soggy.
Arrange them in a single layer in a glass casserole dish (note: 8x8 is prob. fine).
Spread 1/2-inch layer of mascarpone mixture on top of the ladyfingers.
Sprinkle with 1/4 cup cocoa.
Repeat this for the second layer.
Cover and chill in the refrigerator for at least two hours before serving.