For the crêpes:
For the filling:
For the béchamel sauce:
Make the crepes: Mix the flour, eggs, and a pinch of salt. Slowly pour in the milk and butter, while whisking. Let stand for 30 minutes. Heat a crepe pan over medium-high heat. Pour 3 tablespoons of batter into the pan and tip to cover the bottom. When the top begins to solidify, flip with a heatproof spatula and cook the other side, about 30 seconds. Prepare all the batter in this way.
Make the filling: Defrost the spinach and wring out all excess water. Mix well with all of the other ingredients.
Make the béchamel sauce: Melt the butter in a pan and add the flour a little at a time, whisking constantly. Cook for 2 minutes. In another pan, heat the milk. Add a pinch of salt to the flour and butter and slowly whisk in the boiling hot milk. Cook over low heat for about 5 minutes.
Assemble the crêpes: Preheat the oven to 350 degrees. Place a few spoonfuls of filling onto each crêpe and roll up. Place the rolled crêpes into a nonstick baking dish and cover with the béchamel sauce. Add the tomato sauce over the top. Bake for 20 minutes. Serve hot. Serves 4