Butter

1 Quart Heavy Whipping Cream

Optional
To make a tangier, Irish-style butter, sour the cream first. Stir in 1/2 cup yogurt with live cultures and allow to stand at 100F to 115F for 6-10 hours until cream thickens noticeably. You have just made sour cream. Save a bit for your next potato if you like.

Butter making should start with the cream (or sour cream) at refrigerator temperature: 40F or below. Put the cream in a food processor, turn it on, and let run. The process will take a few minutes. The cream will whip within the first 30 seconds. Let it go. Then it will seemingly not change for a couple of minutes. Then the cream will start to get really thick and sluggish and then suddenly break separating into a liquid (the original buttermilk) and butter. Let the processor run for another 20 seconds or so until the butter collects in a lump. Dump the lump into a colander and rinse with could water. Shake off as much of the water as possible. 

Makes about 1 1/2 pounds of butter.

If the plan is to make whipped butter, go right to that recipe while the food processor is still dirty.