
Preheat the oven to 180°C/350°F. Set out a small oven-safe casserole dish or Dutch oven, about 24 cm/10 inches wide, with a tight-fitting lid or foil for covering.
Heat the chicken stock until very hot, just below a boil. This helps the rice cook evenly once it goes into the oven.
Add the hot stock to the casserole dish, then stir in the Arborio rice, finely chopped onion, minced garlic, and black pepper. Add the butter and stir briefly to combine.
Cover tightly with the lid or foil and bake for 35 minutes, or until the rice is tender but not mushy. The mixture should still look a little loose when you remove it from the oven.
Uncover and stir the risotto vigorously for 1 to 2 minutes to help release the starches. Add the Parmesan and remaining butter, then keep stirring until the liquid thickens into a creamy, glossy sauce.
Stir in the lemon zest, 2 tbsp lemon juice, parsley, chives, and dill. Taste and add the remaining 1 tbsp lemon juice if you want a brighter finish.
Check the seasoning and adjust if needed. If the risotto becomes too thick, loosen it with 1 tbsp of boiling water at a time until it is soft, creamy, and gently flowing.
Serve immediately while hot and silky, with extra Parmesan on top if desired.