Sausage and Ricotta Baked Cannelloni

Name: Sausage and Ricotta Baked Cannelloni
Ingredients: 6 Tbsp. unsalted butter; 3 Tbsp. all-purpose flour; 3 cups whole milk; 1 oz. Parmesan, grated (about ½ cup); Pinch of cayenne pepper; Pinch of ground nutmeg; Kosher salt; 2 bunches green Swiss chard; 3 Tbsp. extra-virgin olive oil; 1 lb. sweet Italian sausage, casings removed; 1 lb. whole-milk fresh ricotta; 1 lb. fresh pasta sheets (about 16 6x4 pieces) or 12 oz. dried jumbo shells (about 30); 2 cups store-bought marinara sauce (such as Rao’s); Grated Parmesan (for sprinkling)