Preheat oven to 180 C degrees.
Take 16” round cake tin/pan and line it with a parchment paper.
Combine all three flours, salt, baking soda in a large bowl.
In a separate bowl whisk together the milk, oil and vanilla extract.
Add the wet ingredients to the dry ingredients in the bowl. and mix them together with a silicon spatula till well combined.
Gently fold in the frozen blueberries.
Pour this whole wheat blueberry cake batter in the prepared tin and bake for 40-50 minutes.
Let it cool on a wire rack before slicing it.