Make the sauce first: in a saucepan add the mayonnaise, sweet chili sauce, lime juice, and sriracha.
Bring the sauce to medium heat until it comes to a slight simmer. Give it a quick whisk and set aside for later.
Then add the shrimp into a large bowl and add the pressed garlic, garlic powder, dried parsley, paprika, salt, black pepper, and red pepper flakes (optional).
Mix everything together thoroughly.
Add the unsalted butter to a large skillet and bring it to medium high heat.
Then cook the shrimp in the skillet for about 2-3 minutes per side. In the meantime, cook the spaghetti in a pot of well salted boiling water. Drain and set aside.
Now add the cooked pasta to the skillet of shrimp along with the reserved sauce.
Notes
Don't overcook the sauce- You don't want the sauce to reduce and thicken, so only simmer it gently and then take it off the heat.
Mix the seasonings well- Either pre-mix the seasonings before adding them to the shrimp or mix them thoroughly so that the shrimp are coated evenly with each one.
Use shrimp that is already prepped- Choose shrimp that is already deveined and peeled to save yourself lots of time prepping.
Cook the pasta al dente- The pasta will cook a little as it sits in the hot sauce, so cook it al dente so that it doesn't overcook when combined with the sauce and shrimp.