1. 1. Heat olive oil in a large Dutch oven or pot over medium heat. Add shredded rotisserie chicken and sauté for 5-6 minutes until warmed and lightly golden. Remove chicken to a plate.
2. Add butter to the pot. Once melted, toss in diced onion, carrots, and celery. Sauté 5 minutes until softened.
3. Stir in minced garlic and cook 1 minute until fragrant.
4. Sprinkle flour over veggies. Whisk 1-2 minutes to form a roux (this thickens the broth).
5. Slowly pour in chicken broth while whisking to avoid lumps. Add milk, thyme, rosemary, parsley, salt, and pepper. Bring to a simmer.
6. Stir in frozen peas and cooked chicken. Simmer 10 minutes until slightly thickened. If too thin, mix 1 tablespoon cornstarch with 2 tablespoons cold water for a slurry; stir in and cook 2 minutes.
7. Meanwhile, make dumplings: In a bowl, stir Bisquick and milk just until combined (lumps are okay; do not overmix).
8. Drop dough by heaping tablespoons (about 12-14 dumplings) onto simmering stew, spacing evenly.
9. Cover pot with lid. Reduce heat to low and steam 15-20 minutes without peeking (steam cooks them fluffy). Test doneness with a toothpick; it should come out clean.
10. Remove from heat. Let sit covered 5 minutes. Garnish with extra parsley if desired.