Preheat oven to 350 degrees F (180 degrees C).
To make the filling, combine Fresh Mixed Berries (2 cup), Granulated Sugar (2 tablespoon), and Corn Starch (1 teaspoon) together.
To make your crumble, combine in Butter (3 tablespoon) with All-Purpose Flour (1/2 cup) and Brown Sugar (1/4 cup).
In another bowl, whisk together Whole Wheat Flour (3/4 cup), All-Purpose Flour (1/2 cup), Baking Powder (1/2 teaspoon), Baking Soda (1/4 teaspoon), and Salt (1/8 teaspoon). Set aside.
In your stand mixer, cream together Butter (1/4 cup) and Granulated Sugar (6 tablespoon) until light and fluffy on high speed.
Add in Vanilla Extract (1 teaspoon).
Drizzle in an Egg (1). Mix well.
Next, stir in Plain Yogurt (1/4 cup).
Lastly, fold in dry ingredients on low speed until just combined.
Transfer into a 7-inch square pan lined with parchment paper. Spread evenly.
For the next layer, add the berry filling.
Finally, scatter over the crumble mix into your pan.
Bake it in the oven for about 50 minutes.
Let it cool, cut and serve.