Melt chocolates with butter until chocolates are soft enough to stir smooth. Do not overheat. Addchocolate/butter mixture to powdered sugar and Baileys. Stir until smooth, add nuts and mix well. Place fudge in an 8" X 8" pan, oiled. Lay a sheet of plastic wrap on top and gently press to smooth fudge.
Melt chocolates until soft. Remove from heat. With a fork, beat in butter and Baileys until smooth. Spread topping over fudge with knife. If a very smooth top is desired, place plastic wrap over top as in above. Refrigerate until firm; 1-2 hours. Can be frozen. Using All semi-sweet chips (instead of white chocolate) will yield a deeper, darker fudge.