Preheat oven to 325°F. Line a 9-by-13-inch baking pan with parchment paper, leaving extra parchment hanging over two sides. Lightly coat the parchment with cooking spray.
Combine oats, rice cereal, blueberries, cashews, flaxseed and salt in a large mixing bowl.
Combine rice syrup (or corn syrup), cashew butter and coconut extract in a microwave-safe bowl. Microwave for 30 seconds (or heat in a saucepan over medium heat for 1 minute). Add to the dry ingredients and stir until evenly combined. Transfer to the prepared pan and firmly press into the pan with the back of a spatula.
For chewier bars, bake until barely starting to color around the edge and still soft in the middle, 20 to 25 minutes. For crunchier bars, bake until golden brown around the edge and somewhat firm in the middle, 30 to 35 minutes. (Both will still be soft when warm and firm up as they cool.)
Let cool in the pan for 10 minutes, then using the parchment to help you, lift out of the pan onto a cutting board (it will still be soft). Cut into 24 bars, then let cool completely without separating the bars, about 30 minutes more. Once cool, separate into bars.
To make ahead: Individually wrap airtight and store at room temperature for up to 1 week.