Preheat oven to 180°C. Put a big pot of water on a stove & bring to a boil on high heat with a lid on.
In the meantime, dice up onion & place in a pot on medium heat with the oil. Fry until translucent. Chop up the cauliflower into inch-sized chunks & place in a medium pot with all the other ingredients (except the mozzarella). Cook on medium until the cauliflower is super soft & falling apart & the liquid is reduced by 1/3.
Take out the herb stems & pour all the ingredients into a blender. Add the cheese & blitz until smooth.
In the boiling water, add the macaroni pasta & cook until just undercooked. Pour the cheese sauce over the pasta, mix about & place into a baking tray.
For the crumble mixture, blitz the almonds until rough. Mix it with the breadcrumbs, chopped herbs, crumbled feta & oil. Layer on top of the mac ‘n cheese. & bake in the oven for 10 mins until golden & delicious.
While it is baking, put together a leafy salad for acidic balance.