Cheesy Sausage and Kale Lasagna

Name: Cheesy Sausage and Kale Lasagna
Ingredients: 1/2 lb. sweet Italian sausage; 1 carrot, peeled and diced; 1 celery stalk, diced; 1 small red onion, finely chopped; 3 cloves garlic, minced; 1 18-oz. jar good-quality marinara sauce; kosher salt; Freshly ground black pepper; 1 tbsp. extra-virgin olive oil; 5 oz. chopped kale; 1 8-oz. container ricotta; 1/2 c. freshly grated Parmesan; 1 large egg, lightly beaten; pinch of nutmeg; 9 no-boil lasagna noodles; 1 12-oz. ball fresh mozzarella, thinly sliced; Freshly chopped parsley, for garnish