Preheat the oven to 190ºC/375ºF/gas 5.
Peel the carrots and onion, then trim and slice along with the fennel (reserving any herby tops, to garnish). Place in a roasting dish, toss with 2 tablespoons of oil.
Roast for 20 minutes, then add the unpeeled garlic cloves. Stir everything thoroughly and return to the oven for 20 minutes more, or until the vegetables are soft and browned.
Remove and discard the papery skins from the garlic cloves. Put the roasted veg in a large pan with the vegetable stock and bring to the boil. Simmer gently for 15 minutes, then liquidise with a stick blender, until completely smooth.
To make the flatbreads, toast the fennel seeds in a dry frying pan for 30 seconds or so, until fragrant. Crush roughly with a pestle and mortar, then pour into a bowl with the flour and ½ teaspoon of sea salt.
Dissolve the yeast and sugar in 100ml of hand-hot (not boiling) water, then add it to the flour mixture with the oil and 60 to 75ml of hot water and mix until you have a soft, but not sticky, dough. Knead for 5 minutes.
Pop the dough into an oiled bowl, cover with oiled clingfilm and set aside to rise in a warm place for 30 minutes. Then, with oiled hands, divide the dough into 8 and roughly roll each one into a thin oval. Stack them up, separating them with baking paper to stop them from sticking together.
Heat a griddle pan until it’s smoking hot and add the flatbreads (you’ll need to do this in batches). Cook for a couple of minutes on each side, until charred and puffed up. Keep warm in a tea towel while cooking the rest.
Gently reheat the soup, and serve with a swirl of cream, a scattering of herby fennel tops (if you have them) and the hot flatbreads.