Preheat the oven to 350 degrees. Grease a 9 x 13 inch pan and set aside, or create a parchment sling by cutting parchment paper a few inches wider than the pan then pressing it inside.
Add the flour, butter, sugars, egg, pecans, and salt to the bowl of an electric mixer. Beat on low speed until the mixture is just crumbly, scraping the sides and stirring often.
Press all but about 1.5 cups of the mixture into the bottom of the pan. Bake for 14 minutes.
Meanwhile, add the oats to the remaining crumble mixture and use your fingers to work the oats into the crumble.
Remove the crust from the oven and dollop with the jam, gently spreading it evenly over the crust. Scatter the oat crumble evenly over the top. Return to the oven and bake for another 25-30 minutes, or until the jam is bubbly and crust is golden brown.
Cool completely before serving, or eat warm from the pan (though you might get more of a scoop than a slice while it's still warm). Bars keep well covered at room temperature for up to 6 days.