Blend cream cheese and butter in a food processor until smooth, 10 to 15 pulses. Scrape down sides of bowl. Add cognac, lemon juice, onion, Worcestershire sauce, hot sauce, salt, and pepper to cream cheese mixture; pulse until blended, scraping down sides 2 to 3 times.
Sprinkle fish into cream cheese mixture and pulse just until blended. Transfer pate to a bowl, cover with plastic wrap, and refrigerate until chilled, 3 hours to overnight.
We caught this bluefish off the coast of Gay Head, Martha's Vineyard on a stormy August morning. We froze the fish right away in zipper bags, and a month later I smoked it in apple wood using the method found in the fantastic blog, Dave's Cupboard.