Preheat the oven to 350 degrees.
Slice the plouts like you would eat them and cut those slices in half. It is not necessarily to remove the skin. Slice the rhubarb into ½ inch pieces.
Combine the fruit, starch or flour, and sugar in a baking dish.
In a mixing bowl, combine the brown sugar and flour. Add the butter. Using your hands rub the butter into the sugar/flour mix until it’s the texture of cornmeal.
Evenly distribute the topping on the fruit. Sprinkle on some demerara sugar on top (optional)
Bake in the oven for 30 to 40 minutes or until the topping has browned and the fruit is bubbling. Allow to cool until the fruit sets up before serving. Can be served warm, cold, or at room temperature.