Soak the raspberries in the beer overnight. Alternatively, soak the berries in sugar and lime juice overnight. Drain the juice and reserve for a glaze, if you wish.
Remove the crescent roll from the tube. Do not unroll. Slice into 1 inch rounds. Using your thumb, press down the centers of the crescent roll rounds - much like you would with a thumbprint cookie.
In a bowl, combine the mascarpone with the 4 tablespoons of sugar. You can add a splash of lime juice if you like, but not necessary. Fill the crescent roll centers with the mascarpone.
Bake at 375 degrees for 14 minutes.