Preheat your oven to 350°F and line an 8×8 baking dish with parchment paper, greasing it first to help the paper stick.
For the coffee cake layer, whisk together the wet ingredients in a large bowl.
Add all the dry ingredients (except blueberries) to the same bowl and mix until well-combined.
Transfer the batter to your prepared baking dish and spread the blueberries evenly on top.
Now, prepare the crumble by mixing all the crumble ingredients until grainy.
Sprinkle the crumble evenly over the cake batter.
Bake for 40-45 minutes.
Once cooled, slice into 12 pieces.
Store any leftovers in an airtight container in the fridge for up to a week. Enjoy your wholesome treat!