In a bowl, whisk together the almond flour, rice flour, cornstarch, Redpath® Granulated Sugar, salt and xanthan gum. Sift mixture into a separate large bowl.

Using a pastry blender or two butter knives, cut the butter into the flour mixture until it resembles coarse crumbs with some pea sized pieces mixed in.

In a small bowl, whisk together the egg whites, egg and water. Pour over the flour mixture and stir until dough begins to clump. Knead dough a couple times to bring together.

Divide dough in half and wrap in plastic; chill for 30 minutes.

Line a 11 x 17 x 1 inch (28 x 43 x 2.5 centimetre) rimmed baking sheet with parchment paper.
Crumble one-half of the dough evenly over the prepared baking sheet. Use your fingers to press the crumbs into the bottom and sides of the pan to about a ¼ inch (6 millimeters) thickness. Place in the refrigerator while preparing the top crust and filling.

Cut off about 1/6 of the second dough half and set aside - this will be used to create the decorative letters.

Place the remaining dough between 2 sheets of parchment paper and roll into a rectangle 11 x 17 inches (28 x 43 centimeters). Remove the top piece of parchment and discard. Place dough with bottom parchment attached on a large baking sheet. Cut out a few decorative vent holes (we used stars). Place in freezer for 15 minutes.

Meanwhile, take the reserved dough and roll out between parchment to a thickness of ¼ inch (6 millimeters). Using letter shaped cookie cutters or a paring knife, cut out desired message.

Preheat oven to 350°F (180°C).

In a large bowl whisk together the cornstarch, lemon zest, and salt. Add the raspberries, lemon juice, and vanilla extract and toss gently to combine.

Beat the egg and water together in a small bowl.

Place the filling in the bottom crust and brush the edges of the dough with the egg wash. Cover with the top crust and press the edges to seal. Brush the top crust with egg wash and affix the letters on top. Brush the letters with the egg wash.

Bake in oven until filling is bubbling and crust is golden; 40 - 45 minutes.

Remove from oven and allow to cool in the pan on a rack. Once cooled, cut into desired sized squares.