Slow Cooker Yogurt

1. Stage

Place four 10-ounce jars in a slow cooker. Fill the slow cooker with water up to 1/3 inch of the jar rims. Remove the jars and set aside.

2. Stage

Cover the slow cooker and preheat on High for about 20 minutes.

3. Stage

Meanwhile, pour milk and milk powder into a saucepan and whisk to dissolve. Heat over medium heat until just steaming and a thermometer reads 179 degrees F (82 degrees C), about 10 minutes. Remove from heat and place the bottom of the pan into a bowl of ice water. Cool milk mixture until the temperature drops to 114 degrees F (46 degrees C). Lift the pan out of the ice water.

4. Stage

Measure about 1 cup milk mixture and pour into a bowl. Stir in yogurt until thoroughly blended. Return yogurt mixture to milk mixture in the pan. Pour milk-yogurt mixture into the 4 glass jars, filling up to 1/2 inch of the rims.

5. Stage

Check that the water temperature in the slow cooker is no higher than 114 degrees F (46 degrees C). If it is cooler, cover and allow to come to temperature. If it is too hot, uncover and turn off the slow cooker.

6. Stage

Set filled jars in the warm water; the water level should be up to the level of yogurt in the jars. Cover with a folded dish towel and then with the slow cooker lid.

7. Stage

Turn slow cooker off. Allow to set for 6 hours, keeping the water at 114 degrees F (46 degrees C) as best you can. Check the temperature with your thermometer after about 2 hours, taking care not to disturb yogurt. If lower than 114 degrees F (46 degrees C), turn the slow cooker to Warm for 10 minutes, then shut off again. Check temperature again at the 4-hour mark and repeat. Do not stir or poke yogurt at all during this time.

8. Stage

Check yogurt after 6 hours by pressing gently on the top or tipping the jars to see if it is set; it is done when yogurt is firm and there is a thin layer of yellowish liquid on the top.

9. Stage

Remove the jars from water and dry them off. Top with clean lids and place in the refrigerator.