Fill a large pot with water and set it over high heat so it can come to a boil for the pasta.

Set a large skillet on the stove near the pot so it is ready for the sauce.

While the water heats, check that the onion is finely chopped, the garlic is sliced, the rosemary is chopped, and the escarole is washed and cut into bite-size pieces.

When the water reaches a full boil, add enough salt so the water tastes lightly seasoned.

Add the penne to the boiling water in the pot and stir well so the pasta does not stick together.

Cook the penne according to the package directions until it is tender but still has a little bite in the center.

While the pasta cooks, pour the olive oil into the large skillet and warm it over medium heat.

Add the chopped onion to the skillet and cook for 4 to 5 minutes, stirring often, until it softens and looks glossy.

Add the sliced garlic, chopped rosemary, and crushed red pepper, if using, to the skillet. Stir for about 30 seconds, just until the garlic smells fragrant.

Add the drained cannellini beans and 1/2 cup of the vegetable broth to the skillet. Stir and bring the mixture to a gentle simmer.

Use the back of a wooden spoon to mash some of the beans right in the skillet. Keep going until about one-third of the beans are broken down and the liquid looks slightly creamy.

Add the chopped escarole to the skillet a few handfuls at a time. Stir after each handful so the leaves start to wilt and make room for the rest.