Blueberry Brownies

Step 1
Preheat the oven to 350 degrees F (175 degrees C). Grease a 8-inch square baking pan.

Step 2
Cook 2 cups blueberries in a large saucepan over medium heat. Add cinnamon and stir. Smash berries gently using a fork or a potato masher, being careful that hot juices do not splash back. Cook until most of the liquid has evaporated and you have a thick syrup, 8 to 10 minutes.

Step 3
Remove blueberries from heat and stir in butter to melt. Add sugar and stir to combine. Pour in eggs when mixture has slightly cooled, 1 at a time, mixing well after each addition. Pour in vanilla extract and stir to combine. Fold in walnuts. Fold flour gently into mixture. Beat well, 60 to 80 strokes, adding up to 1/4 cup additional flour as needed if batter seems too wet. Add remaining 1/2 cup blueberries and stir to combine.

Step 4
Pour batter into the prepared baking pan.

Step 5
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 35 to 40 minutes. Let cool completely before cutting and serving.