Step 1

Cut dark green parts of the leeks off and discard (or use to make stock). Clean the leeks (removing the outer layer if needed), dry well and cut into 2.5 cm / 1 inch segments.

Step 2

Preheat a medium ovenproof dish (I used a 26 cm / 10.2" cast iron casserole dish) on the stovetop, on low-medium heat.

Step 3

Add 1 tbsp of olive oil and once it heats up, arrange leeks on top. Allow them to char gently on both sides. Set aside (if the bottom of your dish is badly burnt, clean it but if it's only just caramelised a little, don't worry).

Step 4

Preheat the oven to 200° C / 390° F. Dilute miso in a splash of plant milk in a bowl.

Step 5

Heat the remaining olive oil in a medium size pot, then add flour. Whisk flour and oil together to form a loose paste. Allow it to cook on low heat for a minute whisking frequently. Do not let it brown, we only just want to cook off the raw flour taste.

Step 6

Gradually add in plant milk then diluted miso paste, mustard and nutritional yeast while whisking the whole time. Allow the mixture to simmer gently until it visibly thickens.

Step 7

Season salt, pepper, a good grating of nutmeg and thyme leaves. I also like a squeeze of lemon, but that's optional. Taste and adjust the seasoning remembering that the leeks go in unseasoned.

Step 8

Mix all of the dry ingredients in a bowl, then rub softened butter into them with your fingers or a flexible spatula.

Step 9

Pour the bechamel into the dish with charred leeks - it should just to cover them.

Step 10

Cover the dish with a lid (or tightly with a piece of kitchen foil) and bake for 15 minutes.

Step 11

After 15 minutes, uncover and bake for a further 10-15, then scatter the topping on top and bake for further 5 (or so minutes until everything is beautifully browned.

Step 12

Divide between bowls and enjoy as a vibrant side or alongside some crusty sourdough bread.