Cut 1 pound zucchini in half lengthwise, then cut crosswise into ½-inch-thick half-moons. Place in a large straight-sided skillet or pot. Mince 4 garlic cloves and add to the skillet. Finely grate the zest and juice 1 medium lemon into the skillet.
Add 12 ounces dried penne pasta, ½ cup whole-milk ricotta cheese, 2 tablespoons olive oil, 1 tablespoon kosher salt, ½ teaspoon freshly ground black pepper, and 4 ½ cups water. Stir to combine.
Bring the mixture to a boil over high heat. Boil, stirring occasionally with a wooden spoon, until the pasta is al dente and almost all the liquid is evaporated, 10 to 11 minutes. Top with chopped fresh basil leaves if desired.
