In a pot of boiling salted water, add spaghetti and cook until 2 minutes shy of being done. Reserve at least ½ a cup of the starchy cooking water before draining.

Meanwhile, in a large dry skillet, over medium heat, cook the sausage, breaking it up in the pan with your spoon. When it’s almost cooked through, add the shallots and cook together with the sausage until shallots are softened and translucent and sausage is cooked through. Remove to a bowl or plate.

In the same pan, add 1 tablespoon of olive oil, then the garlic. Stir, and when garlic becomes fragrant, add the sliced brussel sprouts, along with salt and pepper. Toss together just until brussels sprouts become bright green and soften slightly. You want them to be crisp tender. Remove to a second bowl or plate.

When spaghetti is ready, add the sausage back to the pan, along with the chopped tomato. Toss until tomato softens slightly. Add the spaghetti on top, along with the ½ cup of reserved cooking water, Parmesan cheese, lemon zest, and lemon juice. Toss together. If the spaghetti seems too dry, add more cooking water, or a splash of plain water. Taste for seasoning and adjust with salt, pepper, and more cheese if needed. Add back the brussel sprouts, last minute, and toss gently. Serve immediately.