01 -
Start by getting organized - soften your cream cheese in the microwave for 30 seconds or leave it out for a couple hours. Season your cut-up chicken with salt and pepper. Heat your oven to 350°F and move the rack to the top third.
02 -
Get your spaghetti going in well-salted water, but cook it 2 minutes less than the package says - it'll finish in the oven. Drain when done.
03 -
While pasta cooks, melt 1 tablespoon butter with the olive oil in a pot over medium-high heat. Cook the onion until it starts to brown, about 4-5 minutes.
04 -
Add chicken to the pot and cook until almost done, about 5-6 minutes. Scoop it onto a plate for now.
05 -
In the same pot, add garlic, remaining butter, Italian seasoning, and mushrooms. Cook until the mushrooms release their water and it mostly evaporates, about 5 minutes.
06 -
Turn up the heat to high. Pour in the broth, cream, and softened cream cheese (cut into chunks for easier melting). Stir constantly for 5 minutes to help everything meld together smoothly.
07 -
Turn off the heat. Add the chicken back to the pot along with your cooked spaghetti. Give it all a good stir to coat everything in the sauce.
08 -
Transfer to a 9x13 baking dish, spread evenly, and top with parmesan and mozzarella. Bake uncovered for 30 minutes, then broil briefly for a golden top. Let rest 5 minutes before serving.