Mussels With Kielbasa Horseradish Cream

Name: Mussels With Kielbasa & Horseradish Cream
Ingredients: 4 pounds mussels; 2 tablespoons extra-virgin olive oil, plus more for drizzling; 8 ounces kielbasa, coarsely chopped; 4 cups coarsely chopped green cabbage; 3/4 cup finely chopped onion; 1/2 cup coarsely chopped fresh flatleaf parsley, plus more for serving; 3 tablespoons prepared horseradish; Kosher salt and freshly; ground black pepper; 1/2 cup dry white wine; 1/3 cup heavy cream; Slices of rustic bread, toasted and rubbed with garlic, for serving (optional)