Make the Crêpe Batter

In a bowl, whisk the eggs until smooth. Add the milk and mix well.
Sift in the flour, then add the sugar, salt, and melted (but cooled) butter.
Whisk until the mixture becomes a smooth, thin batter.
Let it rest for 30–60 minutes — this helps the crêpes cook evenly

Cook the Crêpes

Heat a 24 cm (9.5-inch) non-stick pan over medium heat and brush lightly with butter.
Pour about ⅓ cup of batter into the pan, swirling it to cover the surface evenly.
Cook for 1½–2 minutes until the edges lift easily, then flip and cook for 30 seconds on the other side.
Transfer to a plate and cover with a towel to keep soft. Repeat with the remaining batter.

Prepare the Filling

In a skillet, heat the olive oil and sauté the chicken for about 5 minutes, until lightly golden.
Add the garlic and mushrooms and cook over high heat for another 2–3 minutes.
Remove the garlic, sprinkle in the flour, and stir for 1 minute.
Gradually add the warm milk, stirring constantly until the sauce thickens and starts to bubble.
Season with salt, pepper, and nutmeg. Remove from the heat.
Stir in the grated kasseri cheese until melted, then add the red pepper and parsley.
Allow the filling to cool for 5 minutes before using.

Assemble the Crêpes

Preheat the oven to 180°C (350°F) with fan.
Lightly grease a 22×30 cm (9×12 inch) baking dish with olive oil.
Lay one crêpe on your work surface, spoon about 2 tbsp of filling into the center, and roll it up, folding the sides in first.
Place seam-side down in the baking dish. Repeat with the remaining crêpes.

Bake

Pour the heavy cream evenly over the crêpes and sprinkle with grated graviera.
Bake on the middle rack for 20 minutes, until bubbly and lightly golden on top.
Serve warm while still creamy and soft inside.