Preheat the oven to 350º.
In a medium bowl, combine all of the ingredients for the topping. Use your hands to mix the butter well. Place the topping in the refrigerator while you prepare the filling.
Chop rhubarb into small pieces, about the size of your pinky nail.
In a medium bowl, combine filling ingredients and stir until well coated.
Spoon filling into 8 ounce oven safe ramekins until 3/4 full. Fill the rest of the way with the topping.
Place ramekins onto a parchment or foil-lined baking sheet and bake for 30-35 minutes.
Serve and enjoy! I highly recommend topping with vanilla ice cream for maximum yumminess!