How to Make Sugar-Free Homemade Yogurt without a Yogurt Maker

Ingredients:
1 liter of whole milk
1 container of plain yogurt (not skimmed), at room temperature
Instructions:
Heat the Milk:
Pour the whole milk into a large saucepan. Heat it over medium heat, stirring occasionally to prevent a skin from forming on the surface. Heat the milk until it just starts to simmer, then remove it from heat. The temperature should reach about 85°C (185°F), which is hot enough to kill any unwanted bacteria.
Cool the Milk:
Allow the milk to cool down to about 45°C (113°F). You can speed up this process by placing the pot in a cold water bath and stirring the milk occasionally.
Add the Starter Yogurt:
Once the milk has cooled to the correct temperature, add the plain yogurt. This yogurt acts as a starter by introducing beneficial bacteria that will ferment the milk.