Cut the shallot in half, peel it and dice it as finely as you can.
Peel the garlic cloves and dice them as finely as you can.
Bring your vegetable stock to a boil in a 15cm or 6" saucepan and then reduce to a simmer.Cut a small cross in the base of the plum tomatoes and plunge them into the vegetable stock for 30 seconds and then into ice-cold water. You should now be able to peel the tomatoes easily.
Cut the tomatoes into a 5mm (¼") dice and add them to the stock.
Taste your stock and add some salt if required.
Add 30g (2 tablespoons) of the butter to a 28cm or 11" frying pan over a medium-high heat. When it begins to foam, add the shallot and garlic and cook for 3-4 minutes, stirring occasionally.
Add in the rice and stir until it goes translucent at the edges and there is a subtle change in the tone of the sizzle. This should take another minute or two.
Pour in the white wine, stirring continuously until it has pretty much all been absorbed or has evaporated.
Turn the heat down to medium and add the stock a ladleful at a time, stirring regularly, only adding more stock when the previous lot has been almost completely absorbed. There should be a milky/starchy residue coating the base of the pan, but no "pourable" liquid when it is ready for the next ladle of stock.
Place the cherry tomatoes in a baking tray and pour over the balsamic vinegar.
Sprinkle with a pinch of salt and roast in the oven at 200°C or 400°F until the risotto is ready. They will need around 15 minutes in the oven.
When the rice is cooked, add in the remaining 15g of butter (1 tablespoon) and pecorino cheese and stir.
Add a lid and allow to sit for 5 minutes; this stage is really important for a nice creamy risotto.
Stir through the basil leaves before serving and top with the roasted tomatoes.