Melt butter and sugar in a small pot. Cook over medium heat for about 3- 5 minutes until it emulsifies into a bubbly hay coloured foam
Stir in cocoa.
Remove from heat, stir in water and cream
Return to heat and stir sauce for a few more minutes until it reaches a smooth silky consistency. Note: If its still not combining add more water and keep stirring until it’s smooth.
Cool sauce for a few minutes to slightly thicken