Put anchovies into a bowl with milk. Let soak 30 minutes. Drain well, then pat anchovies dry with paper towels.
Chop anchovies finely and put into a bowl with butter and cheese; mix well. Add lemon juice, cayenne, nutmeg and hot-pepper sauce.
In a blender or food processor, process to a smooth puree scraping mixture from sides of bowl occasionally. Add capers and mix well. Spread thinly on toast. Garnish with radish slices and watercress.
NOTE: This mixture will keep in refrigerator for up to 5 days.