An appetizer that works with any type of fish — just toss the seafood of your choice into the blender for your own personalized homemade crab cakes*.
Coat a large skillet with cooking spray; set over medium heat. Melt 2 teaspoons butter in skillet. Add onion; cook, stirring frequently, until onion turns translucent and start to caramelize, about 5–10 minutes. Stir in panko; cook, stirring frequently, until toasted, about 5 minutes. Set aside to cool.
Place crabmeat in a large bowl. Add onion mixture, eggs, sherry, salt, and mustard; mix well. Add mayonnaise and parsley; mix well again.
Working with wet hands, form eight 3-inch crab cakes, about ¾-inch thick; place on a metal baking sheet, cover and refrigerate for at least an hour to help crab cakes stick together while cooking.
Coat a very large skillet with cooking spray; set over medium heat. When skillet is heated, melt 2/3 teaspoon butter. Place a batch of crab cakes in skillet in a single layer and cook until golden, about 3–4 minutes per side; remove to a serving plate and cover to keep warm (or place in a 200 degree oven to keep warm). Repeat with remaining ingredients. Yields 1 crab cake per serving.