Haddock Shrimp Cakes with Basil Mayonnaise

Name: Haddock & Shrimp Cakes with Basil Mayonnaise
Ingredients: 1/2 cup basil leaves; 1/2 cup mayonnaise; Kosher salt; Freshly ground black pepper; 3/4 pound skinless haddock or cod fillet, cut into 1/4-inch pieces; 1/2 pound medium shrimp—shelled, deveined and cut into 1/4-inch pieces; 1/2 cup panko (Japanese bread crumbs); 1/4 cup heavy cream; 1 large egg, lightly beaten; 2 tablespoons finely chopped parsley; 2 tablespoons finely chopped chives; 1 teaspoon finely grated lemon zest; Pinch of cayenne pepper; 4 tablespoons unsalted butter; 2 tablespoons vegetable oil