One-Pot Pasta With Ricotta and Lemon

Kosher salt

short, ribbed pasta, like gemelli or penne

whole-milk ricotta (8 ounces)

freshly grated Parmesan or pecorino (2 ounces), plus more for serving

freshly grated lemon zest plus 1/4 cup lemon juice (from 1 to 2 lemons)

Black pepper

Red-pepper flakes, for serving

thinly sliced or torn basil leaves, for serving (optional)