Position a rack in the center of the oven and preheat to 350ยบ. Butter an 8" square baking pan, or line it with a sling of parchment paper.
In the bowl of a food processor, combine the flour, oats, sugar, salt and cardamom. Pulse a few times to combine. Scatter the butter over and pulse about 20 times, until the mixture begins to clump together.
Remove 1 cup of the mixture and set aside. Press the remaining mixture firmly into the pan, building up a 1/2 inch lip on all sides. Spread the jam evenly over the bottom, then sprinkle the 1 cup crumb mixture over the top. Pat down lightly.
Bake the bars until golden on top, about 45 minutes. Let cool completely, then cut into 12 bars.
The bars are crispest the day they are baked, but will keep for several days in an airtight container at room temperature.
Notes
Nutritional values are based on one of twelve bars.