Preheat oven to 400F.
Trim the brussles sprouts and cut into halves or quarters, depending on size. Place in a large bowl. Toss with the olive oil, 1 teaspoon salt, and 1/2 teaspoon black pepper.
Roast the brussels sprouts for approximately 30 minutes, until they are browning. Toss approximately every 5-10 minutes. When done, remove from oven and set aside.
Pour the stock in a pot and heat over medium low. You want the stock to be warm when adding it to the risotto so that the temperature change does not affect the rice.
While the brussels sprouts are roasting, in a large pot, melt 3 tablespoons of the butter over medium heat. Add the pancetta and onions. Cook until the onion is translucent but not yet browning, and the pancetta is rendered and cooked, approximately 3-5 minutes. (Remove a little of the pancetta for garnishing at the end if desired).
Remove the thyme leaves from the stems and add to the pancetta mixture. Cook until fragrant, approximately 1 minute.
Add the rice and stir. Continue cooking, stirring occasionally. to slightly toast the rice until it is just starting to show a little brown color, approximately 3-5 minutes.
Add the white wine to the pot. Cook until the rice is almost dry, where most of the wine has been absorbed.
Add one cup of stock to the rice. Stir continuously until most of the stock has been absorbed. Repeat this process one cup of stock at a time until the rice is cooked thoroughly. You want the rice to have just a little bit of bite left so that it is not completely mushy. Depending on your rice, you may need more or less stock for the right consistency so start tasting the rice after 4 cups.
When your rice is cooked through, remove the pot from the heat. Add the rest of the butter and Parmesan cheese. It is important to do this before adding salt and pepper because the cheese is salty. Stir to combine.
Taste the risotto and season with Parmesan, salt, and pepper as desired.
Serve with the brussels sprouts on top or mixed in.