Place frozen shrimps in a colander. Thaw with tap water. Drain well. Meanwhile, chop the garlic, onions, and chilies.
Heat oil in a large pan over medium heat. Stir-fry thawed shrimp 1 to 2 minutes, season with salt and pepper. Transfer to a plate with the juices and set aside.
In the same pan, heat the butter. Add garlic, onions, and chilies. Saute until fragrant and translucent. Add the pasta sauce, evaporated milk, stock powder, and sugar. Gently stir and simmer over low heat. Season with salt and pepper. Taste and adjust seasonings.
Add back the shrimp. Stir until it is coated with the sauce. Let it cook for 1-2 minutes more. Turn off the heat then add cooked pasta. If sauce becomes too thick, add some pasta water. Gently toss until the pasta has absorbed the sauce. Sprinkle green onions. Serve immediately and enjoy!