Irish Cream Fudge

Another recipe whose origins I don't recall. It may have been from a friend, though it is likely that I found it online. I've never tried it before, but I'll be making a batch tonight.

Ingredients:
3 cups semisweet chocolate chips
1 cup white chocolate chips
¼ cup butter
3 cups confectioner's sugar
1 cup Irish cream liqueur
1½ cups chopped nuts (optional)

1 cup semisweet chocolate chips
½ cup white chocolate chips
4 tbsp Irish cream liqueur
2 tbsp butter

Directions:
Butter an 8x8" pan.

In the top half of a double boiler, melt the 3 cups semisweet chocolate chips, 1 cup white chocolate chips and ¼ cup butter until soft enough to stir. Stir in the confectioner's sugar and Irish cream until mixture is smooth. Stir in nuts. Place mixture in the prepared pan and lay a sheet of plastic wrap over top; press and smooth top down.

In the top half of a double boiler, melt remaining chocolates until soft. Remove from heat and with a fork beat in the butter and Irish cream until smooth. Spread topping over cooled fudge with a knife. If a smooth top is important, place plastic wrap over the top. Refrigerate until firm, 1 to 2 hours at least. This fudge can be easily frozen.