In a large bowl, using an electric mixer, combine the butter and sugars; beat until creamy. Add the vanilla and salt and beat until well combined.
Add the almond flour and the all-purpose flour into the butter mixture on low speed and beat just until a smooth dough forms.
Divide the dough in half. Wrap one half in plastic wrap and refrigerate for 30 minutes. Press the other half into the bottom of a lightly sprayed 9x13-inch baking pan.
Bake the crust in a preheated 325-degree oven about 20 minutes or until it is just beginning to brown around the edges. Remove from oven.
Place the blackberry jam in a bowl and stir well until it is very smooth. Spread the jam evenly over the partially baked crust. Crumble the refrigerated dough over the jam to form a crumbled topping.
Return the pan to the oven and continue baking about 30 minutes, until the topping is firm and golden crisp. Let cool completely on a wire rack. Sprinkle lightly with powdered sugar before cutting into bars.