in a deep bowl or the bowl for you mixer mix 1 cup of heavy cream with the sugar

stir to dissolve the sugar

run the cocoa through a sifter or fine sieve to remove the lumps

add the cocoa to the cream and sugar and stir well- most of lumps will be gone

pour in the rest of the cream and the vanilla

beat on high speed until the cream is thick and full and stands up in stiff peaks

stop beating when it hits this stage or you will end up with chocolate butter and no it doesn't taste good

if you do not have a mixer you can whip this by hand keep whipping until it stands up in stiff peaks

you may also use a stick blender whipping until it again stands up but keep the stick blender submerged or you will cover your kitchen in whipping cream