In a mixing bowl, whisk together flour and eggs until fully combined. Gradually add milk and water, mixing until smooth. Stir in melted butter and salt. Cook in a skillet until edges are light brown.

In a skillet, heat olive oil. Add onion and sauté until translucent. Stir in garlic, shrimp, and crab meat, cooking until shrimp turns pink. Add mushrooms and deglaze with white wine. Season before removing from heat.

Melt butter in a saucepan, whisk in flour to form a roux. Gradually add milk, stirring until thickened. Season with salt, pepper, and nutmeg. Stir in cheese until melted.

Lay one crepe flat, add seafood mixture and drizzle with béchamel. Roll crepe and place seam-side down in a greased dish. Repeat with remaining ingredients.

Preheat oven to 350°F. Bake crepes for 15-20 minutes until heated through and golden. Garnish with parsley before serving.