Add the olive oil to the instant pot. Heat the oil for about 30 seconds on the saute setting, then stir in the garlic. Saute the garlic until it is fragrant and some pieces are just turning brown.
Stir the chopped potatoes into the garlic-oil mixture in the instant pot. Add 1 cup of the broth.
Close the lid and move the valve to the "sealing" position. Set for 9 minutes on "manual" (or "pressure cook") - adjust to 11 minutes at high altitude or if you want your mashed potatoes to be very creamy. Note it will take about 10 minutes for the pot to come to pressure.
While the potatoes are cooking, mince the rosemary, thyme, and chives.
Once the time is up and the instant pot beeps, do a quick release by carefully moving the valve from the "sealing" to the "venting" position to release the remainder of the steam.
Open the pot to pour in the remainder of the broth, and add the salt, pepper, fresh rosemary, chives, and thyme.
Using a potato masher, mash the potatoes to your desired consistency (see note). Add more broth and salt if needed.
To increase the creaminess and whiteness of the mashed potatoes, stir in coconut milk or dairy milk - I usually add at least a half cup. If you will be reheating the potatoes later, you are likely to add more liquid then. Serve!