If using canned salmon, drain well and remove any large bones and skin, then flake with a fork. If using cooked fresh salmon, flake into bite-sized pieces. Chop cooked shrimp into 1/2-inch pieces.

In a medium mixing bowl combine 2 cups flaked salmon and 1 cup chopped shrimp.

Add 3 tablespoons mayonnaise, 2 tablespoons Greek yogurt, 1 teaspoon Dijon mustard and 1 tablespoon fresh lemon juice. Fold gently to combine, keeping some texture in the seafood.

Stir in 1/2 cup finely diced celery, 2 tablespoons sliced green onions, 2 tablespoons chopped parsley and 1 tablespoon drained capers (if using).

Season the mixture with 1/2 teaspoon Old Bay seasoning, 1/2 teaspoon salt and 1/4 teaspoon freshly ground black pepper. Taste and adjust seasoning or lemon juice as desired. Set aside while preparing bread and oven.

Assembly & bake

Preheat oven to 425°F (220°C). Position a rack in the center of the oven. Line a baking sheet with parchment paper or lightly oil it.

Lightly butter one side of each 4 slices of bread (about 3/4-inch thick). Place bread buttered-side down on the prepared baking sheet. Alternatively, brush with 1 teaspoon olive oil if you prefer.

Evenly distribute the seafood filling among the 4 bread slices, mounding it slightly to cover most of each slice.

Top the seafood mixture with 2 cups shredded mozzarella, dividing evenly so each slice gets a generous covering.

Optional: sprinkle 1 teaspoon lemon zest over the cheese for brightness.

Bake in the preheated oven for 8–12 minutes, until the cheese is melted, bubbly and beginning to turn lightly golden. If you want a more browned top, switch to broil for 1–2 minutes while watching closely to avoid burning.

Remove from oven and let cool for 2 minutes. Sprinkle with 1 tablespoon chopped parsley if desired before serving.