Set the Instant Pot to sauté function. Add butter (and a drizzle of olive oil if desired) to the inner pot.
Add frozen shrimp and cook for 1–2 minutes, stirring often with a wooden spoon.
Stir in minced garlic and a pinch of red pepper flakes if using.
Add lemon juice, kosher salt, and black pepper. Scrape any browned bits off the bottom of the pot.
Pour in chicken stock and stir.
Add dry pasta, gently pushing it under the liquid with a slotted spoon or fork.
Close the lid, set valve to sealing, and pressure cook on high pressure for 4 minutes.
When the timer beeps, perform a quick release.
Open the lid and toss the pasta and shrimp together using tongs.
Plate and garnish with parmesan cheese, fresh parsley, and lemon wedges.
