We skim the milk the following day, so not less than 24 hours after milking. All utensils, containers, lids etc squeaky clean - washed thoroughly and scalded for at least 30 seconds too. Covered and refrigerated until we have enough for a batch of butter, or it’s been there about four days, whichever is sooner.
If it’s for cooking immediately we don’t worry about washing it so much. And don’t need to add salt.
If it’s for eating we wash it thoroughly, until the water runs crystal clear. After the last wash, add a bit of salt. The salt helps the last water to come out when you pat it. Water that’s left in, especailly if some buttermilk remains, is what causes that slightly ripe smell and taste. Salt will help but thorough washing is the biggest factor.
Ours spreads well in our kitchen - usually warm but not hot - but not from the fridge. Despite all I’ve said about washing all the buttermilk out and patting out the last of the water, if you dry it to within an inch of its life, it may be a bit hard and less spreadable
. Experiment with timings, how much to wash, how much salt to use, and so on.
Unsalted butter will freeze and we’ve found that our salted also freezes fine and isn’t any different when thawed. So we make big batches in a food processor, and freeze some. There are 20+ of us here, so we use up a tub within 36-48 hours. Hence we can leave a bit of buttermilk in, so it spreads, and eat it before it goes overripe. You could do the same on a smaller scale, freeze it in sizes that you’ll use within two days.
The tip about ghee is noted - we’ll have a go at that.