1. Bring the chicken stock to a boil and turn the heat down to the lowest setting. Leave it on the stove.
2. In a separate pot, heat the butter and olive oil and sauté the diced celery, onion and garlic until soft and translucent. No not brown it.
3. Add the quartered mushrooms and sauté for 2 minutes. Lightly season with a pinch of salt.
4. Pour in the Arborio rice and mix well. Let it soak up all the butter and oil.
5. Add in 1 ladle of hot stock into the rice and stir the rice gently to absorb the stock and let it slowly release the starch from the rice.
6. Once the rice dries up again, add another ladleful of hot stock to the rice and repeat process until rice is cooked. This whole process should take about 15 to 20 minutes. Be patient and keep stirring gently, only adding the next ladle of stock once the rice dries up.
7. When the rice is cooked, stir in the mascarpone cheese and parmesan cheese. Lightly season with salt and pepper. The consistency of the risotto should be like oozing lava.
8. Fold in the fresh rocket leaves and serve immediately. Drizzle with a little bit of olive oil and a sprinkling of parmesan cheese for garnish.