Marinate shrimp with Cajun seasoning, salt & pepper in a small mixing bowl for 10 minutes.
In a skillet, melt unsalted butter and oil over medium heat. After the butter melts completely, add garlic, XO sauce, & Thai chilies.
Give the mixture a few stirs to combine everything. Then add marinated shrimp to the butter garlic sauce.
Coat the shrimp completely with the sauce.
Once the shrimp are fully cooked (about 5 minutes), add an extra cube of unsalted butter and a teaspoon of Cajun seasoning to the skillet. Then give it a few stirs to blend everything. Turn off the heat and remove the skillet from the stove.
Spoon everything into a serving bowl and garnish with chopped green onion. Serve hot immediately!