Place the chopped rhubarb and sugar in a small saucepan over medium heat.
Cook, stirring occasionally, until the rhubarb has broken down and a sauce forms. Stir in the vanilla, if using.
Let cool and serve on its own, or on top of ice cream or Greek yogurt.
Notes
You can use any variety of rhubarb that you like for this recipe (green varieties, too). The variety will alter the color. Add more or less sugar to your liking. As written, the recipe is sweet enough to eat on its own (it's about as sweet as a homemade applesauce). Serving ideas:
On its own
On top of vanilla ice cream
Stirred into Greek yogurt
Spooned over pancakes or waffles
Swirled into oatmeal
On top of pound cake or angel food cake with whipped cream