In a small bowl, mash the blueberries well.
Add in the lemon juice, maple and chia seeds and whisk together until well combined.
Chill for about 30 minutes or until the jam is set.
In a food processor, combine the almonds and pecans. Pulse for about 5 second intervals until the mixture is a combination of grain like pieces with small chunks. You want there to be some small chunks still so don't over process.
Then add all other crumble ingredients and process until fully combined and dates are broken down.
Set aside about 1/3 c mixture for later.
Press mixture firmly into a parchment lined pan. A 6x8 or 8x8 pan will work, just modify to the thickness you want.
Remove the jam from the refrigerator and spread evenly over top.
Finally, sprinkle the crumble topping over the blueberry jam.
Allow to set in the freezer for about 15 minutes before serving.
Remove and cut into bars. Store in the fridge.