Preheat the oven to 180C/350F. Line an 8 x 8-inch pan with parchment paper and set aside.
In a large mixing bowl, combine all your ingredients, except for your blueberries and mix well.
Fold in half your blueberries using a rubber spatula.
If the batter is too thick, add some milk to thin out. If the batter is too thin, add some extra oats.
Transfer the batter to the lined pan.
Top with remaining blueberries and bake for 15-20 minutes, or until the edges are golden brown and the center comes out just clean with a skewer.
Remove from the oven and allow the blueberry baked oatmeal to cool in the pan for 15 minutes, before carefully transferring to a wire rack to cool completely.