Pour heavy cream into your mixer.

Turn your mixer on low speed and gradually raise it to high speed.

Keep mixing until your cream breaks and separates into butter and buttermilk (You may have to lower the speed slightly to this point to prevent sloshing)

Once your butter has solidified and is sticking to your mixer blade, pour off your buttermilk into a separate container.

Scoop your butter into a bowl and add a few pieces of ice.

Press your butter with a rubber spatula or spoon, draining off the water as you go. Keep going until no more water is coming out or your water runs clear.

If desired, mix in about 1/8 tsp -1/4 tsp salt.

Store wrapped in foil in your fridge. (It will keep for a couple weeks to about a month depending how much of the buttermilk you got out)