Boil the milk (SLOWLY - on medium-low heat) - this will take anywhere from 30 minutes to an hour depending on the size of your pot. It's worth doing it slow to avoid burning your pot (which should still be stainless steel as that's the safest option). Your milk should reach 195 degrees F. If you don't have a thermometer, once it's bubbling - you know you've hit the right temperature!
Once boiled, remove from heat and cool - again, a thermometer will help you out here, as you want it to cool to about 115/120 degrees F. This usually takes about 45 minutes.
Scoop some of the warm (115 degrees F) milk into a bowl and whisk with the skyr, then pour into the large pot with the rest of the milk. Next, stir in the rennet.
Put the lid back on the pot and wrap up in a thick towel (a large bath towel works well) and place into your oven. No need to turn the oven on…it's just an incubator to keep it so that it cools slowly.
After about 10 hours, take out the pot, and you should have milk curds + whey. Cut the curds (if you want…it makes it easier) and scoop them into a pot lined with a strainer and cheese cloth. Basically, you want to strain out all of the whey. I leave this on my countertop for the first hour or so, drain the whey, and then continue the process overnight, or for at least 6 or so hours in the fridge.
From there, you'll have skyr, and more leftover whey liquids.
The skry is now good to eat - although if you want it to be “pretty”, I recommend whipping it up in a food processor or powerful blender.
BONUS TIP: Don't throw out the whey! Use it to soak beans, nuts and grains ;)
*NOTE: The nutritional facts do not match up with end product here, as the whey is being removed…so don't take the nutrition facts in this recipe too seriously - instead, look at the nutritional facts of a single serving of skyr.