Prep
Preheat oven to 350°F (175°C).
Line an 8x8-inch baking pan with parchment paper.
Mix Dry Ingredients
In a large bowl, combine oats, whole wheat flour, baking powder, baking soda, cinnamon, and salt.
Mix Wet Ingredients
In a separate bowl, whisk together Greek yogurt, honey (or maple syrup), eggs, melted oil, and vanilla extract until smooth.
Combine
Pour wet ingredients into dry ingredients.
Stir gently until just combined.
Toss blueberries lightly in a small amount of flour, then fold into batter.
Bake
Pour batter into prepared pan and spread evenly.
Bake for 30–35 minutes, until the top is golden and a toothpick inserted in the center comes out clean.
Cool & Serve
Let cool in pan for 10–15 minutes before slicing.
Serve plain or with yogurt, honey, or fresh berries.