Preheat the oven to 350.
Start with the crust/dough first. Add all dry ingredients to a bowl and mix well.
Add in the butter and, using a fork or pastry blender, cut the butter into the mixture until the butter has broken down to pea size and the dough has become somewhat cohesive, but still has a crumbly texture.
Grease well, or line an 8X8 baking pan with parchment paper. Press ½ of the dough mixture into the bottom of the pan, pressing down lightly to create a sturdy crust.
Bake for about 15-16 minutes until the crust has just lightly turned golden. Remove and let chill, slightly pressing the crust down to create a sturdy base.
While the crust is baking, add all filling ingredients to a saucepan and mix well.
Place the saucepan on the stove over medium-low heat until the berries have broken down and the mixture has become jam-like. It should thicken up as you cook it. This should take around 8-10 minutes. Set aside the berry mixture to cool.
Once the base crust is pre-cooked and has cooled slightly, and once the berry mixture has cooled , it is now time to finish assembling the bars.
Pour the berry filling on top of the crust. Using a spatula, smooth the filling over the entire crust evenly.
Using the remaining crust dough, loosely crumble the topping evenly over the top of the berry filling.
Place in the oven for about 16 minutes, until the crumble topping is golden brown. Allow the bars to cool completely, then cut them into bars and enjoy!