Melt the butter until it is hot and bubbly on low-medium heat.
Add the sugar.
Stir or whisk often until the sugar is fully dissolved.
You may also use a microwave oven, but you MUST make sure that each step is repeated individually until everything is fully melted and dissolved before moving onto the next step. Depending on the strength of your microwave, this could take a few times in and out of the oven.
No matter the stovetop or microwave oven method, stir often. Be patient, it will be so worth it!
It will "souffle-up when it is ready for the cream to be added. Add the cream slowly.
Stir in the vanilla and stir until blended and smooth.
The butter sauce can be made ahead of time and stored in the freezer.