In a large sauté pan over medium high heat, warm olive oil and add pancetta. Stir often, until pancetta begins to brown and crisp.
Add shredded sprouts and incorporate into the pancetta and oil, scraping up any bits on the bottom of the pan. Cook over medium high heat, stirring often, until sprouts begin to wilt and turn bright green, about 7-9 minutes.
Squeeze the juice of a lemon over the pan, season sprouts with salt and pepper and taste. Sprouts should still be a little crunchy.
Remove from heat, and toss sprouts with butter, lemon zest, and Parmesan cheese. Serve immediately.