Preheat oven to 350F
Slice the tops off the tomatoes and set aside. Scoop out the seeds and pulp from the tomatoes with a teaspoon, but be careful not to cut through to the base. Chop the pulp and seeds. Toss the hard, central core.
Heat the oil in a medium saucepan and add garlic, sauteing for 2 minutes. Add rice, chile flakes, onions, zucchini and mushrooms, stirring over low heat for 2 minutes.
Pour in the stock then stir in the fresh herbs, tomato pulp and seeds.
Cook for 15 minutes, stirring frequently until rice is tender and liquid has been absorbed – add extra stock if necessary.
Turn off the heat, add Parmesan. Season with salt and pepper and stir well.
Put the tomatoes in an ovenproof dish and fill each one generously with the risotto. Replace tomato tops and bake, uncovered, for 15-20 minutes until the tomatoes are tender. Cool for 5 minutes, then garnish with fresh thyme or basil.
