Gnocchi with Sausage and Broccolini

1 pound store-bought gnocchi
2 tablespoons unsalted butter
1 sweet onion, sliced
2 garlic cloves, minced
1 pound cooked Italian sausage, sliced
1 bunch broccoli rabe, cut into bite-size pieces
1/2 cup chicken broth
Salt and freshly ground black pepper
1/2 teaspoon red-pepper flakes (optional)
1/2 cup grated Parmesan cheese
1/4 cup chopped fresh parsley

Bring a large pot of salted water to a boil. Add the gnocchi and cook until the pasta floats to the surface, 4 to 5 minutes. Drain the gnocchi.

In a large skillet, melt the butter over medium heat. Add the onion and sauté until translucent, 4 to 5 minutes. Add the garlic and sauté until fragrant, 1 minute more.

Add the sausage and cook until it begins to brown, 3 to 4 minutes. Add the broccoli rabe and chicken broth, and bring to a simmer.

Continue to cook, tossing frequently, until the broccoli rabe is wilted and tender, about 5 minutes. Season with salt, pepper and red-pepper flakes (if desired).

Stir in the gnocchi, Parmesan and parsley, and toss well until combined. Serve immediately.