Preheat oven to 350F, line an 8×8-inch pan with foil for easier cleanup, and spray with cooking spray; set aside.To a large bowl, add the pancake mix, water, vanilla, and stir to combine; set aside.To a medium bowl, add the blueberries, flour, and toss to coat the blueberries.Add the blueberries and all flour that’s at the bottom of the bowl to the bowl with the pancake mix and stir to combine.Turn batter out into prepared pan, smoothing the top lightly with a spatula.Evenly sprinkle with additional blueberries for both taste and visual appeal.Bake for about 20 to 22 minutes, or until set and a toothpick inserted in the center comes out clean or with a few moist crumbs, but no batter. Baking times will vary based on brand of pancake mix used so bake according and until done. Start checking at 15 minutes; you don’t want to overbake this at all or they will be dry and dense. Serve with maple syrup, dust with confectioner’s sugar, or use your favorite pancake topping. Squares are best warm and fresh but will keep airtight in the fridge for up to 5 days. Reheat gently before serving.