Boil heavily salted water in a large pot. Cook pasta until al dente. This should take 4 minutes. Be sure to drop pasta in the water once the sauce is almost complete, as angel hair cooks very quickly.
To a bowl, season the shrimp with cajun seasoning, smoked paprika, and garlic powder.
To a skillet on medium high heat, add in the oil and butter. Once melted add in shrimp and sear on both sides until 90% cooked through. Remove from pan and set aside.
Lower your heat to medium. Add in bell peppers, onion, and scallion. Sauté until onion is translucent. This should take 2-3 minutes.
Add in garlic and sauté until fragrant.
Add in salt, pepper, and red pepper flakes. Stir until black pepper is fragrant.
Add in tomato paste and cook until burgundy, This should take 2 minutes.
Follow with vodka and be careful not to burn yourself if a flame arises. Scrape up any bits in the bottom of the pan. Allow the vodka to reduce by half.
Add in heavy cream and lemon juice. Stir until combined well. Follow with parmesan cheese. Lower heat to a simmer.
Add shrimp back into sauce and follow with angel hair straight from the boiling water. Mix well and add in any pasta water to achieve desired consistency of the sauce.
Garnish with parsley and lemon zest. Serve immediately. Enjoy.