Preheat oven to 350 degrees. Line a 9- by 13-inch baking dish (a lasagna pan) with a piece of parchment paper large enough to extend over the sides of the dish.
Place the blanched almonds into a food processor and pulse several times until they are ground into a meal. Add ½ cup brown rice flour, the corn or tapioca starch and salt and pulse a few times to combine. Add ½ cup of butter and the almond Cake & Pastry filling and process until fully combined. Spread the mixture into the prepared baking dish in an even layer. Bake for 20 minutes.
While the base layer bakes, prepare the topping by combining the remaining ½ cup brown rice flour with the gluten free oats, brown sugar and cinnamon. Stir to combine. Add the remaining 4 tablespoons of butter and work it into the mixture with your fingers until crumbly (or you can use a pastry cutter). Stir in the sliced almonds.
When the base layer has cooked, spread the Mixed Berry Pastry Cake & Pastry Filling on top in an even layer. Sprinkle the topping all over in an even layer and bake for another 20 – 25 minutes or until the berry filling is bubbly and the topping lightly browned. Let cool in the pan. Once cooled, place a sturdy cutting board next to the baking dish, lift the baked pastry out of the pan using the parchment paper and place it on the cutting board. Cut into 16 bars approximately 2 by 3 inches each.
Notes
(If you don’t have a food processor and almond flour is available to you, substitute 1 cup almond flour for the blanched almonds, cut the butter into the flour mixture with a pastry cutter and blend the remaining ingredients for the base layer in a mixer.)