Cook the pasta in a large pot of boiling salted water until al dente.
Meanwhile, cook the bacon, stirring occasionally, in a large skillet over medium-high heat until crisp; drain, reserving some of the bacon fat. Using the same skillet, cook the garlic and Brussels sprouts, stirring occasionally, until golden, about 5 minutes.
In a large bowl, whisk together the eggs and sprinkle with plenty of pepper. Add the drained pasta, bacon, Brussels sprouts and some of the reserved bacon fat, if using; toss to combine. Serve with the pecorino, if using.