Instructions

1. Since we’re going to be growing a culture in it, it is super important that a 6 or 8-quart Instant Pot's stainless steel, lid, and sealing ring are nice and clean. Hot soapy water and a hot rinse before drying with a clean kitchen towel should do the trick.
2. Pour 8 cups milk into the Instant Pot. Lock the lid in place but leave the pressure valve open (you can also cover with a glass lid if you have one). Press the yogurt button until it says boil, then press start. It will take 25 to 35 minutes, and the Instant Pot will beep when the boiling cycle is complete. Stay close, as your model may take more or less time to come to temperature.
3. Use a thermometer to test the milk’s temperature, it should be around 180ºF. Remove the insert and let cool at room temperature until the milk is 110ºF, about 1 hour. Alternatively, you can cool the mixture by filling your sink with ice water and gently submerging the bottom of the insert in the ice water — this will take about 10 minutes.
4. If a skin has formed on top, remove and discard it. Transfer 1 cup of the warm milk to a small bowl, then stir in 2 tablespoons plain yogurt and any desired add ins. Return the yogurt mixture to the Instant Pot and whisk gently to combine. Return the insert to the Instant Pot (make sure the bottom is dry if you used the water cooling method).
5. Lock the lid in place but leave the pressure valve open again. Press the yogurt button once more until it reads 8:00 (8 hours), then press start. This will begin a count up clock on the incubation period. After about 3 hours the yogurt will begin to thicken. Start checking the thickness and flavor at about 6 hours by gently dipping a spoon into the yogurt. Avoid mixing the yogurt while it cooks, or you’ll have very loose yogurt. 8 hours of cooking will yield perfectly thickened and delightfully tangy yogurt — about what you’d expect from typical whole-milk yogurt. You can continue to cook the yogurt for 2 hours more for thicker, tangier yogurt.
6. Remove the insert and lightly cover with plastic wrap. Refrigerate until chilled through, at least 4 hours or up to overnight, the yogurt will thicken slightly more when chilled. Transfer to airtight containers and refrigerate for up to 2 weeks. Remember to save some of this yogurt to use as the yogurt starter if you plan on making more yogurt in the near future.