This is so easy - you have to try it!
Greek Yogurt with Pineapple (recipe adapted from Tasty Kitchen)
Heat 2 quarts (8 cups) milk to 180 degrees (I guessed - I don't have a candy thermometer) stirring frequently. It took about 15 minutes. Cover and cool to about 116 degrees (I cooled it til I could stick my finger in it and not scream, lol).
Remove 2 cups of milk to a bowl and whisk in 4T plain yogurt. Whisk that back into the rest of the milk. Put in container and cover tightly; let sit in a warm place for 6-8 hours (I sit mine out overnight) to thicken. Once thickened, place in refrigerator for 4 hours. Remove and strain - mine sat in the fridge straining, fine cloth over a colander sitting over a large bowl - 5 hours to overnight, until desired consistency.
Add desired fruit/whatever to it - I used a few tablespoons of crushed pineapple in juice (not syrup - I have a massive sweet tooth but I don't like sugary things). The only thing I will do differently next time is to drain the pineapple a bit first, it thinned out the yogurt a bit because I didn't. It is also delicious with cut up, slightly overripe peaches, or blueberries ... or just about any other fruit. Try granola on top too!