- Whisk the egg in a large mixing bowl.
- Add the cream, mustard, Worcestershire, Old Bay seasoning, cayenne, and black pepper to taste. Continue whisking until well blended.
- Stir in onions, parsley, mayonnaise, and one-half of the smoked trout.
- Gently fold in the other half of the trout, taking care to break up the trout as little as possible, then add cracker crumbs.
- Press the mixture into a 1 3/4-inch biscuit cutter. Each cake should weigh about 2 1/4 ounces.
- Remove cake from the cutter and place on a parchment-lined baking sheet, cover, and chill for one hour.
- Lightly coat the cakes in breadcrumbs.
- Sauté the cakes over medium heat in butter in a large, heavy skillet for 2-3 minutes on each side or until golden brown.
- Serve trout cakes warm with a tablespoonful of crème fraîche or sour cream, if desired.