Creamy Reuben Chowder with Rye Croutons

Name: Creamy Reuben Chowder with Rye Croutons
Ingredients: 1 Tablespoon unsalted butter; 1 Count large onion, very thinly sliced; 0.75 Pound pound smoked ham, diced; 0.75 Pound andouille sausage, halved lengthwise and sliced 1/2 inch thick; 1.5 Tablespoon all-purpose flour; 4 Cup low-sodium chicken broth; 1 Pound sauerkraut—drained, rinsed and squeezed dry (1 1/2 cups); 0.25 Cup crème fraîche; 0.25 Cup snipped chives; 6 Count slices of rye bread, cubed and toasted; 0 prepared horseradish, for serving