Add the cream to the bowl of a mixer. Use the whisk attachment to start whipping the cream.

The cream will become whipped cream with stiff peaks. Continue beating on high until the cream separates. The butter will start to collect inside the whisk and separate from the buttermilk, about 10 minutes.

Use a strainer to strain out the buttermilk into a bowl. This can be saved and used for any recipe calling for and will keep in the fridge for 2-3 weeks.

Transfer the butter to a bowl and cover with cold water. Use your hands or a spatula to knead the butter and rinse out the excess buttermilk. Empty out the water and continue with fresh cold water until the water is clear as you knead the butter.

At this point you can add salt to the butter or leave it out for unsalted butter.

Wrap the butter in wax paper or parchment and store in an airtight container in the fridge.