Cut the florets off the broccoli. Peel any particularly tough parts from the exterior of the stalk, and cut the stalk into quarters lengthwise. Place all the broccoli on a baking tray, and drizzle with oil. Roast at 180°C (Gas Mark 4 / 350°F) for around 20 minutes (depending on exactly how big you cut your broccoli) - it should be lightly browned, and mostly softened up.

While the broccoli is roasting, heat another dash of oil in a large saucepan. Add the garlic, and cook over a medium heat for a couple of minutes until soft and fragrant. Add the diced potatoes, vegetable stock, dried herbs, and a generous pinch of black pepper. Bring to a simmer, and cook for around 15 minutes, until the potatoes are very soft.

Add the roasted broccoli to the pan (hold back a few pieces for garnish, if you like), and use a hand blender to blend the soup to your liking - I left mine with a little texture.