Wash and rinse the chicken thighs under cold water, then pat them dry with paper towels. Trim off any excess skin and fat using kitchen scissors. Season both sides of the chicken thighs with salt and ground black pepper, and set aside.
Turn on the Sauté mode on your Instant Pot. Once the pot is fully heated (to ensure the chicken doesn’t stick), add 1/2 tablespoon of the olive oil.
Pan-sear the chicken thighs (skin side down first) until both sides are nicely browned. (You may also pan-fry the chicken in a regular or non-stick skillet.) Discard the excess chicken fat from the Instant Pot by spooning it out.
Add the remaining olive oil and sauté the garlic for a short time. Then, add the mushrooms, chicken broth, whipping cream, salt, and cayenne pepper. Cover the pot, select Manual, and set it to High Pressure for 10 minutes.
When it beeps, perform a Quick Release. Once the valve drops, carefully remove the cover, add the lemon juice and chopped parsley, and stir to mix well. Switch to Sauté mode for a few minutes to reduce the sauce, and adjust the seasoning with more salt and lemon juice to taste.
Serve immediately with plain spaghetti.
