Cook pasta per box directions. Once cooked, drain pasta reserving 1/2 cup of pasta water. NOTE: Do not allow pasta or pasta water to cool before adding to sauce.
Peel, devein, wash, then drain shrimp. Season with 1 Tbsp cajun seasoning, set aside and keep cool until needed.
In a large skillet, fry bacon, set aside on paper towels while leaving bacon fat in skillet.
Over medium high heat, sear shrimp in bacon fat for one minute on each side then remove and set aside. NOTE: Do not overcrowd shrimp to allow for caramelization.
Add 1 Tbsp butter to the skillet and add diced onions. Saute on medium heat until tender.
Add smashed garlic, sliced mushrooms, and a splash of either white wine or chicken broth. Cook over medium heat for an additional 3-5 minutes.
Slowly pour in heavy cream and 1 cup of chicken broth. Add in dry seasonings and bring this to a simmer.
In a separate bowl, whisk together remaining 1/3 cup of chicken broth with cornstarch to make a slurry. Make sure there are no lumps and slowly add to thicken sauce. Let this cook for 5-7 minutes.
Add in warm pasta water, shrimp, and crumbled bacon pieces. Bring this back to a simmer for an additional 3-5 minutes. Toss with cooked pasta and serve garnished with diced green onions (optional).
