Silky Cup-Set Whole and 2% Milk Yogurt

Steps

1. Wash a heavy pot, a whisk, a ladle, a thermometer and four 1-cup (250 ml) jars with lids in hot soapy water, then rinse them with boiling water and let them air-dry on a clean towel.
2. Set the Greek yogurt starter on the counter so it loses its chill while the milk heats.
3. Pour the whole milk and the 2% milk into the pot and heat over medium-low, stirring often so it doesn't scorch, until it reaches 180°F (82°C), about 15–20 minutes.
4. Hold the milk blend at 180–185°F (82–85°C) for a full 20 minutes, stirring now and then and adjusting the heat; this long hold gives the lighter milk blend a smooth, custard-like set.
5. Take the pot off the heat and let the milk cool to 108–112°F (42–44°C), about 30 minutes, or set the pot in a sink of cold water and stir to speed it up. Skim off any skin.
6. In a small bowl, whisk the Greek yogurt starter with a ladleful of the warm milk until completely smooth, then stir this mixture back into the pot of milk gently but thoroughly.
7. Ladle the cultured milk into the four jars, dividing it evenly (about 250 g each), and cap them loosely.
8. Incubate the jars undisturbed at 108–112°F (42–44°C) for 6–8 hours, in an oven with only the light on or in a cooler with jars of warm water; check with the thermometer and don't jostle the jars. It's ready when it holds together and pulls away cleanly from the side when tilted.
9. Tighten the lids and refrigerate the jars immediately at 40°F (4°C) or below for at least 4 hours to firm up and finish the flavor. A thin layer of whey on top is normal; stir it back in for the softest texture.
10. The yield is about 1,000 g, four 250 g cups, unstrained. Serve plain, adding any fruit or sweetener only after culturing, and keep refrigerated for up to 2 weeks.