In a small saucepan, add the diced apple, 0 calorie brown sugar, lemon juice and ground cinnamon. Give them a quick mix to coat the apple chunks and set over low heat to soften. Cook the apples, stirring occasionally until they're soft and have released most of the water, about 5-7 minutes. Remove from the heat and set aside to cool.
In a small bowl, mix together the butter, 0 calorie brown sugar, flour, oats and ground cinnamon until well combined. It might be easier to use your hands to create a soft, crumbly mixture. Set aside.
Transfer the slightly cooled apple chunks to a 9cm ramekin, cover with the crumble and place in the oven. Bake for 20 minutes or until the crumble turns a golden brown. Set aside to cool for a few minutes.
Serve and enjoy! I love to top mine with a little greek yogurt or for an even more indulgent treat, with a little vanilla ice cream!
Notes
Substitutions:
*0 calorie brown sugar - can be subbed for any 0 calorie granulated sweetener. The sweetener I used is a 1:1 ratio of sweetener to sugar so bear that in mind when using a different sweetener. *Light butter - can be subbed for an equal amount of unsweetened applesauce or regular butter.