Begin by preparing the vegetable mixture. Heat the oil in a large frying pan, and add the garlic, broccoli and red onion. Cook over a medium-low heat for 5 minutes, stirring regularly, and then add the sweetcorn, cherry tomatoes, artichokes, chickpeas, spinach and chives. Cook for a couple more minutes until the spinach has wilted, and then set aside.

Next, make the sauce. Melt the 20g of butter in a saucepan, and turn the heat down low. Add 1 heaped tablespoon of flour, and whisk into the butter. Cook for 1 minute, stirring constantly, to cook the flour. Then add the milk about 50ml at a time, whisking until smooth before adding a little more. When you have added all the milk and the sauce is smooth, add the stock, and stir again to combine. Season generously with black pepper.

Add the vegetables to the sauce, and mix to combine. Set aside.

At this point, heat the oven to 190°C (Gas Mark 5 / 375°F).

Finally, make the crumble topping. Rub the flour and butter together with your fingertips until the mixture resembles breadcrumbs. Add the oats, grated cheese and pesto, and mix thoroughly until the pesto is evenly distributed.

Transfer the vegetables and sauce to a baking dish, and add the crumble topping. Bake for around 30 minutes, until the topping is crispy and the sauce is bubbling.