Preheat the oven to 375ºF. Then, Bring a large pot of salted water to a boil. Add pasta. 

Cook the pasta for 4-6 minutes. The pasta should be slightly undercooked because it will cook for an additional 20 minutes in the oven. 

Strain the water from the pasta and set pasta aside.  

Next, season the chicken chunks with ranch seasoning. Be sure that the ranch seasoning covers every chunk of chicken.

Heat a large oven-safe skillet or deep cast-iron skillet over medium/high heat. Add olive oil.

When olive oil is fragrant add chicken. Cook the chicken for 1-2 minutes on each side. Only partially cook the chicken. It will cook for an additional 20 minutes in the oven. Remove from heat.

Add red pepper, bacon, ranch dressing, and pasta into the large pan and toss. Set aside.

When the saucepan is hot, add butter. When the butter has melted add flour to the saucepan and whisk together. When the butter and flour form a paste or crumble, slowly pour the milk into the saucepan, whisking consistently while pouring. 

Whisk the mixture over medium heat until the milk mixture begins to thicken (about 4-5 minutes). 

Remove from heat and add the mozzarella cheese and salt to the saucepan. Whisk until the cheese sauce is thick and creamy. 

Carefully pour the cheese sauce over all of the pasta and chicken mixture and toss. Make sure all of the ingredients are covered by the cheese sauce. 

Then, place the casserole dish into the oven, uncovered, and bake for 20 minutes. 

Remove from the oven and sprinkle with parmesan cheese and place in the oven for an additional 5 minutes to melt the cheese. 

Finally, remove the casserole from the oven and enjoy!