Easy Cheesy Leeks

• olive oil↗1 tbsp tbsp
• butter↗20g g

  plus extra for the pan

• leeks↗6

  washed and thinly sliced

• garlic cloves↗2

  crushed and peeled, left whole

• thyme sprigs↗10g g
• parmesan↗50g g

  or vegetarian alternative, finely grated

• fresh breadcrumbs↗50g g
• butter↗20g g
• plain flour↗20g g
• whole milk↗300ml ml
• whole nutmeg↗½

  grated

• Dijon mustard↗1½ tbsp tbsp
• Gruyère↗75g g

  or vegetarian alternative, grated

• soft cheddar↗150g g

  grated

Step-by-step instructions

1. 1

   Heat a large deep pot over medium‑low heat and melt the olive oil and butter. When foam appears, add the leeks, garlic and thyme together with a generous pinch of salt.

2. 2

   Cook for 25‑30 minutes covered, stirring frequently, until the leeks are completely softened and begin to caramelize at the edges. Remove the thyme sprigs and discard them.

3. 3

   Meanwhile, prepare the sauce. Melt the butter in a saucepan over medium heat, then add the flour and stir. Cook for 1 minute. Gradually pour in the milk in a thin stream, whisking constantly until you obtain a thick sauce, about 6‑8 minutes. When the sauce boils, remove from heat and add grated nutmeg, mustard and both cheeses. Season, then add the leeks.

4. 4

   Preheat the oven to 200 °C/180 °C with convection/gas 6. Lightly butter a baking dish about 23 cm in diameter. Mix the parmesan and breadcrumbs with a generous pinch of black pepper.

5. 5

   Pour the leek mixture into the dish. It can be stored in the refrigerator for up to two days and in the freezer for up to a month. Sprinkle with parmesan crumbs and bake for 25‑30 minutes (5 minutes longer if chilled, and another 10‑15 minutes if frozen) until golden.