Preheat oven to 350 degrees. Line an 8-inch square baking pan with foil so that it drapes a couple of inches over two sides.

In the bowl of a stand mixer, add the flour, oats, brown sugar, baking powder and salt and mix together with a whisk.

Attach the bowl to the mixer and with the paddle attachment running on low, add the butter, one piece at a time until well-incorporated. Add the walnuts and continue to mix until it looks like wet sand.

Using your hands, press 2/3 of the dough firmly and evenly into the bottom of the prepared baking pan.

With a spoon, spread the jam evenly over the dough. Sprinkle the remaining 1/3 of the dough evenly over the jam. You will see the jam peeking through.

Bake until the top is browned, about 40-45 minutes.

Let the bars cool in the baking pan for 30 minutes.

Lift the foil and bars out of the pan and carefully peel the foil off the edges. Cut into 16 squares. Store in an air-tight container for up to 5 days or 2 weeks in the freezer.