fettuccine with asparagus and peas

Ingredients

• 8 ounces uncooked fettuccine
• 2 medium leeks, white portion only, sliced
• 1 tablespoon olive oil
• 1 pound fresh asparagus, trimmed and cut into 1-inch pieces
• 2 cloves garlic, minced
• 1 cup frozen peas, thawed
• 1/2 teaspoon salt
• 1/4 teaspoon pepper
• 1/2 cup part-skim ricotta cheese
• 1/4 cup plus 6 teaspoons grated parmesan cheese, divided
• 2 tablespoons lemon juice
• 1 tablespoon grated lemon peel