Preheat your oven to 375°F (190°C).

In a large mixing bowl, combine shrimp, crab meat, cheddar cheese, cream cheese, mayonnaise, mustard, Old Bay seasoning, garlic powder, and black pepper until well combined.

Open the refrigerated biscuit dough and separate each biscuit.

On a floured surface, roll out each biscuit to about 1/4 inch thick.

Place a generous spoonful of the filling in the center of each flattened biscuit.

Fold the dough over to create a half-moon shape, pinching the edges tightly to seal.

Line a baking sheet with parchment paper and space the filled biscuits evenly.

Melt butter and brush it over the tops of each biscuit.

Bake for 15-20 minutes until golden brown.

Allow to cool slightly, then garnish with fresh parsley and serve warm.