Whisk the flour, eggs, milk and a pinch of salt together until smooth, then stir in the melted butter.

Rest the batter for 10 minutes at room temperature so the flour hydrates fully.

Heat a lightly buttered 8-inch nonstick pan over medium heat.

Pour in about 60 ml of batter, swirl to coat the pan thinly, and cook 1 to 2 minutes per side until pale gold with light brown spots.

Stack the cooked crespelle on a plate with parchment between layers while you make the filling.

Wilt the spinach in a dry pan over medium heat for 3 minutes, then cool and squeeze out excess water.

Chop the spinach and mix with ricotta, 50 g parmesan, egg yolk, nutmeg, salt and pepper.

Melt the butter in a saucepan over low heat, whisk in the flour, and cook 1 minute until pale and foamy.

Add the milk gradually, whisking constantly, and cook 5 to 6 minutes until the sauce coats the back of a spoon.

Season with nutmeg and salt.

Heat the oven to 200C/390F.

Spread a thin layer of béchamel across the bottom of a 9x13-inch baking dish.

Spoon filling down the center of each crespella, roll it up, and arrange seam-side down in the dish.

Pour the remaining béchamel over the top and scatter with the remaining 50 g parmesan.

Bake for 20 minutes until golden and bubbling at the edges.

Rest for 5 minutes before serving.