This is from Bon Appetit, I made a couple changes. Next time I would add more brussles sprouts.
2 TBSP olive oil, divided
1/2 pound Brussels sprouts, shredded in a food processor
8 oz pasta
4 oz pancetta, finely chopped
1/2 tsp black pepper
4 TBSP butter
1/3 c grated Pecorino plus more
2 large egg yolks, beaten to blend
Heat 1 TBSP oil in a large skillet over high heat. Working in batches, add Brussels sprout leaves and cook, tossing occasionally, until charred in spots and crisp-tender, about 5 minutes; transfer to a plate and set aside. Wipe out skillet.
Cook pasta in a large pot of boiling salted water, reserving 1 cup pasta cooking liquid.
Meanwhile, heat remaining 1 tablespoon oil in same skillet over medium heat. Add guanciale and cook, stirring often, until slightly crisp, about 4 minutes. Add pepper and cook, stirring, until fragrant, about 30 seconds. Immediately add 1/2 c pasta cooking liquid to keep pasta from burning; reduce heat to low and gradually add butter, swirling skillet.
Add pasta to skillet and toss to coat. Add Pecorino; toss to combine. Remove from heat; mix in egg yolks. Add reserved Brussels sprout leaves; toss, adding pasta cooking liquid (or hot water) as needed to thin sauce.
Serve pasta topped with more Pecorino.