Gather your cooked chicken and shred it into bite-sized pieces.
Cook the rotini pasta in a large pot of salted boiling water until al dente, about 8-10 minutes. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Sauté diced onion for 3-4 minutes until translucent, then add minced garlic and cook for 1 minute.
Stir in shredded chicken, frozen mixed vegetables, dried thyme, dried rosemary, salt, and black pepper. Cook for 5 minutes.
Reduce heat to low, add cream of chicken soup and milk, stirring until well combined.
Add cooked rotini pasta to the skillet and gently stir until evenly coated with the sauce.
Sprinkle shredded cheddar cheese on top, cover, and let it heat for 2-3 minutes until cheese melts.
Serve warm, garnished with fresh herbs if desired.