Porrelloni (Leek Cannelloni)

Method

1. Cut the leek lengthwise and separate the layers to obtain large sheets. Blanch them in salted boiling water for about 1 minute, then transfer to ice water to cool. Drain and pat dry.
2. Prepare the béchamel: melt butter in a saucepan, add flour and cook the roux. Add all the milk at once and whisk until smooth. Remove from heat and stir in Parmesan, egg yolk, and tomato concentrate. Set aside.
3. Boil potatoes until tender, then mash them. Mix with chopped mint, grated pecorino, olive oil, salt, and pepper to taste.
4. Lay a leek sheet flat on a work surface. Pipe a line of filling along one edge. Roll up tightly like a cannelloni. Repeat with remaining sheets and filling.
5. Lightly grease a baking dish and spread a thin layer of béchamel on the bottom. Arrange the leek cannelloni seam-side down in the dish.
6. Cover with the remaining béchamel. Sprinkle breadcrumbs and extra Parmesan on top.
7. Bake in a static oven preheated to 180-200°C (350-400°F) for about 20 minutes, until golden and bubbly. Serve hot.
8. Optional: garnish with extra mint leaves or Parmesan before serving.