Preheat oven to 350°F. Coat a 13x9x2-inch baking pan with baking spray.
In a small bowl, whisk together the whole wheat flour, spelt flour, 1/2 cup oat flour, salt, baking powder, cinnamon, and baking soda.
In a large bowl, stir together the brown sugar, eggs, mashed banana, butter, and vanilla until smooth. Add the flour mixture and stir until combined. Add 2 cups of the oats and stir to combine.
Transfer ¼ cup of the oat batter to a small bowl. Add 3 Tbs. oat flour and ¼ cup rolled oats and stir to combine until the mixture forms clumps.
Spread the batter in the prepared pan and spread the jam in an even layer over the batter. Sprinkle the reserved oat clumps over the jam. Bake for 20 to 25 minutes or until the crumble turns golden brown.