Set Lids to Simmer. It is not necessary to sterilize jars due to the heat in the pressure canner. It is not recommended either due to the water causing issues with canning your butter. Add butter to a large pot and slowly melt.
Once melted, heat to a roiling boil (not a fry). You have enough butter that it will roll instead of sizzle.
Fill jars with melted butter to 1/2" headspace. Make sure to add some white milkfat to each jar as you fill. CAREFULLY whip the rim of each jar with white vinegar making sure that you do NOT get any vinegar into the jar. Doing so will cause that jar to curdle as it's a dairy product.
Process in a pressure canner for 75 minutes. Use 10 lb pressure for a weighted gauge canner or 11 lbs for a dial gauge. When time is up, turn off heat and allow pressure to release naturally.
After release, remove jars from canner and set on a town. Allow to rest approx. 20 minutes. At the 20 minute mark, shake each jar vigorously to recombine ghee and milk fat. Repeat the shaking process every 20 minutes until ghee and milk fat is fully combined. Jars may ping before they are fully combined. Once combined, allow to sit 8-12 hours until fully cooled.
Wiping the rim of the jar is incredibly important. It helps to remove butter residue from the rim ensuring that you get a good seal.
How to Can Butter in a Pressure Canner https://sixdollarfamily.com/how-to-can-butter-in-a-pressure-canner October 7, 2020