Pre-heat oven to 350*F.
In a bowl, whisk together all of your crust ingredients (except the butter).
Add the melted butter and mix until everything is crumbly. Set aside.
In another bowl, add all of your filling ingredients except the rhubarb and xanthan gum. Mix until smooth.
Add the rhubarb and xanthan gum to the rest of the filling ingredients and mix well until the mixture has coated the rhubarb.
Grease an 8x8 inch dish with oil or butter and pour half of your crumble crust mixture over the bottom of the pan (you can even it out but it doesn't have to be pressed in or anything).
Next, evenly pour your filling over the crust and then top it with the rest of the crumble mixture.
Bake for 25-30min or until crust has browned and filling is bubbly.
Serve warm with a dollop of homemade whip cream or low carb vanilla ice cream. Enjoy The Best Keto Rhubarb Crisp! (You can store this covered in the fridge for up to 7 days).