Fettuccine with Leeks and White Beans

Ingredients

• 2 tablespoons olive oil
• 1 pound leeks ((about 1 bunch), sliced and cleaned)
• Coarse salt and ground pepper
• 2 cans ((15 1/2 ounces each) cannellini beans, drained and rinsed)
• 3 1/2 cups chicken or vegetable broth
• 1/2 teaspoon sage
• 12 ounces fettuccine
• 2 tablespoons fresh lemon juice
• 1/2 cup heavy cream
• 1/2 cup finely grated Parmesan cheese (, plus more for serving)
• 1/4 cup coarsely chopped fresh parsley (, (optional))