Melt chocolates with butter until chocolates are soft enough to stir smooth. Do not overheat. Add chocolate and 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.