Coarsely chop broccoli into small bite-sized pieces, if necessary.
Halve and peel onion. Cut halves into ¼" dice.
Lightly crush croutons.
Pat chicken breasts dry and, on a separate cutting board, cut into ¾" dice. Season with a pinch of salt and pepper.
Sear the Chicken
Place a medium pot over medium-high heat and add 1 Tbsp. olive oil. Add chicken and onions to hot pot and stir occasionally until onions are softened and chicken reaches a minimum internal temperature of 165 degrees, 5-7 minutes.
Remove to a plate. Reserve pot; no need to wipe clean.
While chicken cooks, combine cornstarch and milk in a mixing bowl.
Cook the Broccoli
Return pot used to sear chicken to medium-high heat and add 2 tsp. olive oil.
Add broccoli, half the seasoning (reserve remaining for soup), and 2½ cups water to hot pot. Bring to a boil, then cook until broccoli is bright green, 3-4 minutes.
Finish the Soup
Stir cornstarch-milk mixture to recombine.
Add cornstarch-milk mixture, chicken and any accumulated juices, onions, remaining seasoning, cheese, and a pinch of pepper to pot.
Bring to a boil, then reduce to a simmer. Cook until thickened, 1-2 minutes.
Finish the Dish
Plate dish as pictured on front of card, garnishing with crushed croutons. Bon appétit!