Savory Tart

Preheat the oven to 350 degrees F (200 degrees C).
In a medium bowl, stir together the whey, almond flour, baking soda and salt.
Cut in the butter using a pastry blender or your fingers until the butter lumps are smaller than peas. Stir in the water to form a stiff dough.
On parchment paper, place 16 balls of dough a few inches apart. Shape with hands into rectangle shapes (This recipe will make a batch of 16 2 1/4″ x 3″ rectangles or ovals.).
Beat the egg and brush it over the entire surface of the rectangles. Even the “insides” of the tart; the egg is to help glue the lid on.
Place a heaping tablespoon of desired filling into the center of each rectangle, keeping a bare 1/8-inch perimeter around it. Fold the other side over and using your fingertips, press firmly around the pocket of filling, sealing the dough well on all sides. Press the tines of a fork all around the edge of the rectangle. Repeat with remaining tarts.
Gently place the tarts on a lightly greased or parchment-lined baking sheet. Prick the top of each tart multiple times with a fork; you want to make sure steam can escape, or the tarts will become fluffy pillows instead of flat toaster pastries (my mistake number 1).
Bake for 10-12 minutes in the preheated oven, until edges are lightly browned. Cool in oven to crisp up.