Fit your food processor with the S blade attachment(you could also use a blender/coffee grinder). Add the biscuits and grind until very fine. Transfer to a bowl and add the powdered sugar and peanut butter. Mix to combine. Mixture will be thick. Set aside.

In a large bowl or the bowl of a mixer fitted with the paddle attachment, add the eggs, oil, juice, and vanilla. Mix to combine.

Add in the sugar and mix to combine. Add the flour and baking powder and mix with a spoon or spatula till combined. Turn out the dough on to a clean surface and knead gently until the dough is nice and smooth(this doesn't take long, maybe 1 minute).

Take a small chunk of dough and roll it out onto a silicone baking mat(this helps it not to stick to the counter). Keep the dough a tad thick. With the rim of a glass cup, cut out circles of dough. You can fill these with whatever you like! For PB & J: In the centre of each circle, place a ball of peanut butter filling. Next to it a dollop of strawberry jam. Pinch the top sides together create a corner. Continue with the other two until you have a triangle. If using the dough immediately, it should stick easily together. If you refrigerate the dough overnight or for a couple hours, you may need to brush the edges of the circle with egg wash before folding them.

combine one egg and 1 tsp of water in a bowl. Whisk with a fork and brush onto the edges of the cookie to help the sides stay together during baking.

Preheat your oven to 350 F. Bake the cookies for 15-18 minutes, keeping an eye on them and taking them out when the edges are just starting to turn golden. Enjoy!!