Fill a large pot with water and salt it generously. Bring it to a rolling boil over high heat. Add the fettuccine and cook according to the package directions until al dente, usually around 9 minutes.

Before draining, scoop out half a cup of that starchy pasta water and set it aside. Drain the rest and set the pasta aside.

Melt 2 tablespoons of butter in a large skillet over medium heat. Add the sliced zucchini in a single layer. Cook for about 4 minutes, stirring occasionally, until edges are slightly golden.

Add the halved cherry tomatoes, minced garlic, and kosher salt into the skillet. Cook for another 4 to 5 minutes without stirring too much, allowing the tomatoes to blister.

Reduce heat to low, add the remaining 2 tablespoons of butter, lemon zest, and lemon juice into the skillet. Pour in the reserved pasta water and stir until combined into a glossy sauce.

Add the drained fettuccine into the skillet and toss until evenly coated with the sauce. If the sauce looks too thick, add more reserved pasta water.

Remove from heat, stir in the grated Parmesan, and sprinkle fresh parsley over the top. Serve immediately.