Keto Breakfast Casserole

Name: Keto Breakfast Casserole
Ingredients: 2 tablespoons unsalted butter, at room temperature; 1 medium turnip (about 8 ounces), peeled and cut into 1/2-inch dice; One 8-ounce bag radishes (about 1 bunch), halved if small and quartered if large; 1/4 medium celeriac (about 4 ounces), peeled and cut into 1/2-inch dice; 1/2 teaspoon ground cumin; Kosher salt and freshly cracked black pepper; 1 pound fresh chorizo, removed from casings; 1 small red onion, cut into 1/2-inch dice; One 8-ounce block Monterey Jack cheese, grated; 3 cups packed baby spinach; 1/3 cup heavy cream; 12 large eggs; Sour cream, for serving