In a large, sturdy pan, melt the butter on a low heat. Once butter is melted add the diced onions and soften. About 7 minutes. Add the crushed garlic and cook until fragrant. Usually 1 minute.
In a pot on the stove, keep your chicken broth or stock on a low heat to keep it warm for adding to the risotto.
Once the onions are softened, add the risotto rice and the diced courgette. Increase the heat and sizzle for about 1-2 minutes.
Squeeze the lemon juice onto the risotto rice and add one ladle of chicken broth. Bubble on a medium-high heat while constantly stirring. Once the chicken broth is almost absorbed into the rice, add another ladle full of chicken broth. Keep cooking the risotto like this for 20-25 minutes, until it is tender.
Stir in the mozzarella, mascarpone, and your seasoning to the risotto. Cover with a lid and let sit on a low heat for 5 minutes.
Once the 5 minutes is done, remove the lid and stir the risotto getting into the corners so that the whole pan looks creamy.
Remove from heat and serve.