Preheat oven to 400°F. Spread the sprouts and sliced onions in an even layer on a baking sheet. Drizzle 1 tbsp of olive oil over the top of the vegetables.

Remove the loose outer papery skin from the head of garlic. Slice off just enough of the top of the garlic to expose the cloves. Place the garlic on a piece of tin foil and drizzle 1 teaspoon of olive over the top of the cloves. Wrap the garlic in the tin foil and place it on the baking sheet with the other veggies. Roast the veggies for 30 minutes.

While the veggies roast, boil the pasta according to package directions. Drain and set it aside. 

Heat 1 teaspoon of olive oil in a 10-inch pan over medium heat. Add the pancetta and cook it in the oil until it starts to release its fat. 

When the garlic is roasted, remove the foil so the garlic can cool for a few minutes. Once it's cool enough to handle, squeeze the softened cloves out of the bulb. Chop the cloves and smoosh them with the back of your knife until they form a paste.

Add the roasted vegetables and cooked pasta to the pan with the pancetta and stir to combine. Add the roasted garlic, lemon juice, parsley, and cheese. Stir again and serve.