You can use blueberries in place of cherries here, and frozen fruit works just fine! Come up with your own flavor combinations and let us know how it goes (you can tag your bars @gourmandisela ).
Ingredients
Cherry Filling
12ozFresh or frozen cherries
1tspKosher salt
2tbspSugar
1tspFresh lemon juice
2TbspWater
2TbspFlour
Cherry Bar Crumble
6ozMelted butter
1cupWhole wheat flour
1cupAll purpose flour
1/2tspBaking powder
1/2tspBaking soda
1cupRolled oats
1cupBrown sugar
1tspKosher salt
2Egg whites
1/2cupToasted pistachios
Instructions
Cherry Filling
Preheat the oven to 350F. Place the cherries in a medium to large pot and bring them to a simmer with the salt, lemon juice and sugar over medium heat.
Stir the water and flour to make a thick paste. Once the cherries are bubbling, add the paste and stir until thickened. Set aside while you make the crumble.
Cherry Bar Crumble
Melt the butter and pour over the sugar. Stir in the remaining ingredients, followed by the egg whites.
Line an 8"x8" pan with parchment paper (we like using two sheets arranged like a + sign). Press 2/3 of the crumble into the bottom of the pan. Drop the filling over the bottom, then the remaining crumble over the fruit. Top with pistachios.