Preheat your oven to 350 degrees F and line a 8x8 baking pan with parchment paper, set aside.
In a medium bowl make your crumble topping by combining the flour, sugar, brown sugar, and melted butter until crumbs form. Chill in the fridge until ready to use.
In a large bowl, whisk together your brown sugar, sugar, egg, and vanilla extract until light and fluffy, about 1 minute. Then whisk in the melted butter. Once combined, fold in your flour, baking powder, and salt.
Evenly spread your batter in your prepared baking pan. Top with an even layer of your blueberry jam. Sprinkle your crumble topping over top of the blueberry jam.
Bake for 28-30 minutes, or until the edges are golden brown and the middle a bit puffy.
Allow to cool in your baking pan for at least 15 minutes before transferring to a cooling rack. Enjoy!