Heat olive oil in a large pot over medium heat. Add diced chicken and sliced sausage. Cook for 5–7 minutes, stirring occasionally, until chicken is browned and sausage is slightly crisp. Add diced onion and minced garlic, cooking for 2–3 minutes until fragrant and softened.
Stir in chicken broth, heavy cream, ranch seasoning mix, and pasta. Bring to a boil, then reduce heat to low. Cover and simmer for 10–12 minutes, stirring occasionally, until pasta is tender and has absorbed most of the liquid.
Remove from heat and stir in shredded cheddar cheese until melted and smooth. Adjust consistency with extra broth or cream if desired.
Taste and season with salt and pepper. Garnish with chopped parsley and serve warm.