Whole Milk Set Yogurt with Vanilla-Berry Swirl

Steps

1. Wash and sanitize a heavy pot, whisk, thermometer and four 8-ounce jars with lids by rinsing them in boiling water.
2. Heat: pour the commercially pasteurized whole milk into the pot and heat over medium-low, stirring often, until it reaches 180°F (82°C). Hold it at 180–185°F (82–85°C) for 10 to 20 minutes, stirring so it doesn't scorch.
3. Cool: take the pot off the heat and cool the milk to 108–112°F (42–44°C), about 30 to 45 minutes, or faster in a sink of cold water, checking with the thermometer.
4. Add starter: in a small bowl, whisk the plain yogurt with live active cultures with a ladle of the 108–112°F (42–44°C) milk until smooth, then stir this mixture back into the pot.
5. Incubate: divide the cultured milk evenly among the jars, cover and keep undisturbed at 108–112°F (42–44°C), such as in an oven with only the light on, for 6 to 8 hours, until set and it pulls cleanly from the jar side when tilted.
6. Refrigerate: move the jars to the fridge immediately at 40°F (4°C) or below and chill at least 2 hours to firm up. This makes about 4 cups of yogurt.
7. While the yogurt chills, make the sauce: in a small pan, simmer the raspberries, blueberries, sugar and lemon juice over medium heat for 6 to 8 minutes until jammy. Off the heat, stir in the vanilla, then cool and refrigerate.
8. In a dry skillet, toast the pumpkin seeds over medium heat for 3 to 4 minutes until they pop, then cool.
9. To serve, spoon a quarter of the vanilla-berry sauce over each jar of chilled yogurt and scatter a quarter of the pumpkin seeds on top. Keep the yogurt refrigerated and use within 1 to 2 weeks.