Place the blueberries and the dates in a pot over medium-high heat. Cover and cook for 10 minutes, stirring twice. Uncover, lower heat to medium, and continue to stir for about 3-4 min.
remove from heat and allow to cool. Puree till smooth.
Scoop the blueberry filling into a zip-seal plastic bag for easy piping later on. Store in the fridge.
Liquefy the banana with brown sugar, cinnamon, and vanilla. Stir in the two flours and the baking powder and soda
Cut out 10 strips of parchment paper, 2.5 inches wide.
Divide the dough into four equal parts, and shape into logs.
Sandwich the logs in between two strips of paper, roll them flat (1/8th inch). Trim them up and roll the scraps between the remaining two strips of paper.
Let them chill in the fridge again (the dough gets sticky fast), then remove the top layer of paper.
Cut a 3/4 inch corner off of the ziplock bag where you've stored the blueberry filling, and pipe it down the center of the dough. I recommend keeping the dough strips in the fridge and only removing one at a time to pipe the filling on. Flatten the filling a little with a knife.
Measure every two inches of dough and cut, then fold the dough over the filling. There will be some filling that remains uncovered
You can also fold, THEN slice, but I find makes for messier edges. Don't try to separate the cut parts -- you'll do that after baking, like a pizza.
Preheat the oven to 350 and continue to chill the bars.
Put the strips directly onto the baking sheet and bake for 10 min
You can cut the bars right away (separate them) or wait until they've cooled a little. The bars will soften after a few hours, and this is when they start to get sooo good. Honestly, wait about two hours before taking a bite.
Serve with love, makes about 24 bars. Keep in fridge in airtight container for up to 1 week.