Heat the oven to 425°F. Lightly oil a 3-quart baking dish.

Set a large deep skillet on the stove over medium heat and add the olive oil.

Add the chopped onion and 1/2 teaspoon of the salt to the skillet. Cook for 5 to 6 minutes, stirring often, until the onion is soft and lightly golden at the edges.

Add the chopped garlic, dried oregano, and red pepper flakes if you are using them. Stir for about 30 seconds, just until the garlic smells fragrant.

Pour the crushed tomatoes and vegetable broth into the skillet. Stir well and bring the sauce to a gentle simmer over medium heat.

Add the drained cannellini beans to the skillet. Stir them into the sauce and cook for 3 minutes so they warm through.

Add the baby kale to the skillet a few handfuls at a time. Stir after each addition until the leaves wilt down into the sauce.

Add the black pepper and the remaining 1/2 teaspoon salt to the skillet. Stir, taste the sauce carefully, and add a little more salt if it tastes flat.

Add the gnocchi to the skillet. Stir well so the gnocchi are coated and mostly tucked down into the sauce.

Add half of the shredded fontina and 1/4 cup of the Parmesan to the skillet. Stir gently until the cheese is mixed through the sauce.

Transfer the gnocchi mixture from the skillet to the prepared baking dish. Spread it into an even layer.

Sprinkle the remaining fontina and the remaining 1/4 cup Parmesan evenly over the top of the casserole.