Add the milk and vanilla bean paste to your slow cooker, cover and cook on low for 2 hours. At this point, check the temperature of the milk using a candy thermometer or something similar. Once the milk has reached 180 degrees F, turn the slow cooker off and let the milk stand at room temperature for about 1 1/2 hours, or until the milk has reached about 105 degrees.
Ladle 2 cups of the milk into a large measuring cup and whisk in the yogurt. Transfer the mixture back to the slow cooker and whisk to combine. At this point, you can add any additional flavorings. I only use the vanilla bean paste, but you can add in additional flavorings (vanilla extract, honey, jam, etc).
Taking paper towels or a thin dish cloth, place it over the slow cooker, leaving a bit of overhang. Place the lid back on and place the slow cooker in an undisturbed dark and warm place. I place it in my pantry. Let the yogurt sit for about 8 hours.
After about 8 hours, check the yogurt and make it has thickened substantially. If it hasn't, place the towel and lid back on. Let it stand until the desired thickness has been reached. (NOTE: It usually only take me about 8 hours, but on occasion, it has taken 10-12 hours depending on the temperature of the room.)
At this point, you can continue on and make this yogurt "Greek," or just refrigerate it and treat it as plain yogurt. I tend to make it the "Greek-style" to get rid of any whey, but this is up to you. To continue on making this yogurt "Greek," refrigerate the yogurt for 2-3 hours or until thickened substantially. Remove it from the fridge. Layer about 5 sheets of cheesecloth on a strainer that sits above a bowl. Pour the yogurt on top and let it stand for about an hour. Transfer the yogurt to an airtight container and refrigerate until you are ready to eat. You may also choose to strain the yogurt a second time after it has chilled for a second time. The first time may not be enough to get rid of the whey. Do this as many times as you feel necessary.
Prepare your stone fruit granola bowls by layering homemade vanilla bean yogurt and stone fruit over your favorite granola. Enjoy immediately!