How to Make It
Heat butter in a large Dutch oven over medium-high until melted. Add onion, and cook, stirring often, until translucent, 4 to 5 minutes. Add salt, pepper, and garlic; cook, stirring often, until fragrant, about 1 minute.
Stir in broth and Alfredo sauce; bring to a boil. Add peas and chicken; cover, and reduce heat to low. Simmer until peas are tender and chicken is heated through, 5 to 7 minutes.
Divide pasta among 6 bowls; ladle soup over pasta. Sprinkle with parsley and pepper.