Heat the oven to 180C - put the chopped vegetables into a roasting tin and tuck the garlic cloves in amongst the veggies, drizzle with olive oil, sprinkle over the fennel seeds, oregano and season with salt and pepper. Roast for around an hour or until everything is nice and cooked through and just browning.
Once the vegetables are roasted - tip them and any juices into a blender (you may need to do this in two batches depending on how large your blender is) As you blitz slowly pour in the hot vegetable stock unitl you have a lovely thick soup.
Transfer to a saucepan to serve.
For the spicy prawn topping - add a glug of olive oil to a frying pan - tip in the prawns, sprinkle over the chilli flakes, lemon zest and juice and season as you wish with salt and black pepper. Cook the prawns until they're cooked right through properly. Then sprinkle on the chopped flat leaf parsley.
To serve - ladle soup into bowls and top with spicy prawns.