Preheat your oven to 350 degrees. Spray a small glass baking dish (8×8 or 8×11) with non-stick spray.
In a large bowl, combine the flour, brown sugar, oats, salt and baking soda. Mix well until all of the ingredients are combined and no sugar clumps remain. Using your hands, “smoosh” the room temperature butter into the dry mixture. Mix it very well until it is of even consistency. It should resemble a sandy/crubmbly mixture (see photos below).
Evenly sprinkle half of the crumb mixture into the bottom of your glass pan. Press it down to make it compact. Carefully distribute the jam over the pressed crumb mixture. Drop the jam down in small bits because if you try to spread it, it will pull the crumb topping up off of the bottom of the dish. Keep the jam about 1/2 inch away from the edges so that it does not burn on the glass while baking. Sprinkle on the remaining half of the crumb mixture. Pat down lightly but do not completely pack it in like the bottom layer.
Bake the jam bars for 35 minutes or until it is golden brown on top. Let cool for 10 minutes then cut into 12 or 15 squares.