Lightly sautée onions and garlic in clarified butter. Pound black pepper roughly in a mortar and add to the onion and garlic.
Deglaze with wine, let the liquid reduce by half, and then add beef stock. Crack green pepper in a mortar, but don't mash it.
Add green pepper, allspice and bay leave to the sauce and let it simmer to reduce the liquid.
Crumble pumpernickel bread and pound it in a mortar to a paste. Add milk and pumpernickel to the sauce and let it reduce until it thickens.
Season with heavy creme or creme fraiche, molasses or Worcestershire sauce, and whiskey, and let the pepper sauce reduce until it gets the desired consistency. If you'll serve the pepper sauce with steaks, fry the steaks, then deglaze with the sauce, and finally add whiskey.