Pour the heavy whipping cream into the bowl of a stand mixer.
Using the whisk attachment, beat the cream on medium-high speed. The cream will first become whipped cream before continuing to separate.
Continue mixing until the butter separates from the buttermilk. You will see solid yellow butter clumps and thin, milky buttermilk.
Strain the butter from the buttermilk, reserving the buttermilk for baking or other recipes.
Place the butter in a bowl and rinse it with very cold water. Gently press and knead the butter to remove as much remaining buttermilk as possible.
Continue rinsing and pressing until the water runs mostly clear.
Mix in the salt, if desired.
Shape the homemade butter into a log or place it in a container. Refrigerate until ready to use.
