How to Make It
Line a 7 1/2-by-3 1/2-inch loaf pan with plastic wrap, leaving plenty of overhang. In the bowl of a food processor, combine the tuna, butter, cream, lemon zest, lemon juice, cayenne, anchovies and the 3 tablespoons of capers. Season with salt and pepper and process until smooth. Scrape the puree into the loaf pan and smooth the top. Cover with the overhanging pieces of plastic wrap and refrigerate until firm, at least 8 hours or overnight.
In a small bowl, stir the 2 tablespoons of minced capers with the parsley and celery and set aside. Unwrap and unmold the pâté onto a serving dish and sprinkle the parsley mixture on top. Serve chilled with toast or crackers.