You can do this method using a stand mixer, a hand-held mixer, or even with a whisk (if you have a lot of muscle and patience).
Place the cream either in a stand mixer or in a large glass jar (using a hand-held mixer) and mix the cream. It will become whipped cream before becoming stiffer and finally, it will become butter - where the fat solids will separate from the buttermilk liquids.
Drain the buttermilk from the butter, squeezing the butter well to get out as much of the buttermilk as possible.
Step 2: Drain and 'wash' the butter
Wash the butter to remove all the remaining buttermilk - this is important as it will have an impact on the shelf life and flavor of the butter. To do this I fill a bowl with ice-water, add the butter to the water and squeeze it well in between your hands to squeeze out as much of the buttermilk as possible.
Rinse the butter, to get off any remaining buttermilk residue.
Step 3: Add the vanilla
With a small paring knife, cut the vanilla bean in half lengthwise and use the back of the knife to scrape out all of the seeds and add it to a bowl with the butter and mix well to thoroughly combine.
You could also do this in your stand mixer or with a blender to quickly mix the vanilla butter.
Once prepared, either transfer the vanilla butter to an airtight container or scoop it onto a piece of parchment paper/plastic wrap, shape it into a 1-inch log, and wrap it like a Christmas cracker, twisting the ends.
Refrigerate the butter until you're ready to use it.
How To Store
Store the vanilla butter in the fridge for between 1-2 weeks. Alternatively, you can also freeze the butter for up to 6 months.
The buttermilk drained from this homemade butter can be used in any recipe calling for buttermilk. However, it doesn't tend to be as acidic as commercial buttermilk. You can mimic this by adding an extra 1tbsp acid (vinegar or lemon juice) before using it.