Remove your turkey from the package and discard any extra packaging or gravy packets. Rinse the turkey and pat dry.
Cut up your onion and smash your garlic. Stuff the cavity of the turkey breast and carefully place opening down onto the metal rack, not letting the onion or garlic fall out. Place the rack on a plate or cutting board while you prepare the rub.
Soften your butter in a small bowl and add all of the spices. mix together until you have a paste that will easily spread onto the turkey.
Using a rubber spatula, spread the rub paste under the skin, on top of the skin, and on the rest of the turkey until all of its surface is covered.
Place two cups of chicken broth into the instant pot then carefully lower your turkey into the instant pot using the metal rack.
Place the lid on the instant pot.
Set the valve to sealing.
Press "manual" on High Pressure and set the timer according to your turkey breast size (5 minutes per pound) 25-30 minutes for a 5-6 pound turkey suggested in this recipe.
When the instant pot is done cooking, be sure to let the pressure release naturally. Do not manually release pressure. Allowing it release naturally will ensure that the turkey finishes cooking.
When the pressure has been released, carefully open the lid and remove the turkey from the instant pot using the metal rack. The metal rack will be the perfect place for the turkey breast to rest. Allow it to rest for at least 10 minutes before cutting.
Slice the turkey breasts off of the bone as well as any other meat on the bone.