Preheat the oven to 350°F (175°C).

Cook spaghetti in salted boiling water according to package instructions until al dente, about 8-10 minutes. Drain and set aside.

In a skillet, heat oil. Season the chicken breasts with salt and pepper, cook them until golden brown, about 6-7 minutes per side. Remove, cool, and shred.

In the same skillet, fry chopped bacon until crispy, about 5-7 minutes. Transfer to paper towel-lined plate and crumble.

In a mixing bowl, combine cream of chicken soup, sour cream, and half of the cheddar cheese until smooth. Fold in shredded chicken, spaghetti, and crumbled bacon.

Grease a baking dish with oil. Transfer the mixture into the dish, top with remaining cheddar cheese and crumbled bacon, and sprinkle with green onions.

Bake in the preheated oven for 20-25 minutes until cheese is melted and golden.

Let cool for a few minutes before serving warm.