Preheat the oven to 150°C, fan 130°C, gas mark 2. Fry the bacon in a large pan without oil for 5-10 minutes until crisp. Remove from the pan and set aside.
Heat the olive oil in the pan, then add 1 peeled and finely chopped onion and fry for 5 minutes until soft.
Add the Arborio rice and the roughly chopped tomatoes and cook, stirring continuously, for 2-3 minutes.
Pour 500ml of the stock over the rice mixture. Add the cooked bacon and stir through. Bring to the boil, then transfer to a 2-litre baking dish and bake in the preheated oven for 20 minutes.
Remove from the oven and stir. Increase the oven temperature to 170°C, fan 150°C, gas mark 3½. Add the garden peas and the remaining stock, and return to the oven for 20 minutes.
Stir through the parsley, top with parmesan shavings and serve.