In a large skillet, heat 2 tablespoons of olive oil over medium-high heat. Once the oil shimmers, add sliced mushrooms in a single layer. Sear them for about 5-7 minutes until they turn golden brown and release their liquid. Season with salt and pepper for added flavor, then transfer the mushrooms to a plate and set aside.

In the same skillet, add the broken-up Italian sausage over medium heat. Cook for about 5 minutes, stirring occasionally until the sausage is browned and fully cooked, with some crispy bits forming.

Once the sausage is browned, stir in 3-4 minced garlic cloves. Cook for another 1-2 minutes until the garlic becomes fragrant and lightly golden.

Meanwhile, cook your preferred long pasta in a separate pot according to package directions until al dente. Transfer the cooked pasta directly into the skillet with the sausage, along with a splash of the reserved pasta cooking water.

Toss everything in the skillet together, then add a handful of arugula, freshly grated Parmesan cheese, and the zest and juice of one lemon. Stir vigorously for 2-3 minutes until the arugula wilts down and the cheese melts.

Plate the pasta, garnishing with additional Parmesan cheese and a sprinkle of red pepper flakes. Serve immediately while it's warm.