Whisk the Batter: Combine all-purpose flour, eggs, milk, and salt in a bowl. Mix until smooth and well blended, creating a thin batter. Let it rest for about 30 minutes for best results.

Cook the Crepes: Heat a non-stick pan over medium heat; add a small bit of butter. Pour a ladle of batter, swirling to cover the base. Cook for 1-2 minutes until lightly golden, then flip to cook the other side. Repeat until all batter is used.

Make the Béchamel Sauce: In a saucepan, melt butter over medium heat. Whisk in flour to form a roux, then slowly add milk, stirring constantly. Cook until the sauce thickens and is smooth, about 5-7 minutes. Season lightly with salt, black pepper, and a pinch of nutmeg.

Sauté Seafood: In a skillet, heat a little oil over medium-high heat. Add the shrimp, lobster, and white fish, gently cooking until just done (about 3-5 minutes). Sprinkle with fresh herbs and seasoning to taste.

Assemble the Crepes: Take each crepe and fill it with a generous portion of the seafood mixture. Roll or fold the crepes and place them in a baking dish.

Top with Béchamel: Pour the creamy béchamel sauce generously over the assembled crepes, ensuring each one is covered.

Bake (optional): Preheat your oven to 350°F (175°C). Bake the filled crepes for about 10-15 minutes until heated through and bubbly at the edges.