Position oven rack in the centre and pre-heat to 350°F/175°C.
In a saucepan, bring the blueberries, sugar, orange zest and orange juice to a boil. Reduce heat to medium and simmer, stirring frequently for 15 to 20 minutes until reduced by almost half. Set aside to cool completely.
Lightly grease a 9 x 9” baking pan and line with parchment paper.
In a large bowl, using a hand mixer, cream the butter and brown sugar for a minute until fluffy.
In another bowl, mix the flour, oats, almonds, cinnamon and baking powder.
In three intervals, add the flour mixture to the creamed butter and mix with a spoon until crumbly.
Press three quarters of the crumb mixture to the bottom of the lined pan and pour the cooled blueberry jam over top. Sprinkle with the remaining crumb mixture and press down lightly.
Bake for 37-40 minutes until golden brown.
Allow to cool at room temperature, then refrigerate until cold and cut 3” into bars.