Pumpkin Alfredo Sauce

Ingredients

• 6 Tbsp. unsalted butter
• 15-20 fresh sage leaves, plus 2 tsp. finely chopped sage
• 3 Tbsp. flour
• 1 tsp. crushed garlic
• 1 1/2 cups heavy cream
• 1 cup whole milk
• 1 sprig fresh rosemary, finely chopped
• 1 cup canned 100% pumpkin puree, not pumpkin pie filling
• 1/8 tsp. ground cinnamon
• 1/8 tsp. ground nutmeg
• 1 tsp. kosher salt, plus more to taste
• freshly cracked black pepper
• 1/2 cup Parmesan, finely grated (I used a microplane)
• 1 lb. pasta of choice, cooked