In a large bowl, combine flour, protein powder, sugar substitute, and a pinch of salt.
Cut the butter into the dry mixture (in other words, just add small amounts at a time rather than one large scoop of butter) then add 1/3 cup of cold water.
Mix everything up until it comes together to form a dough ball.
Lightly flour a surface (I used parchment paper as my surface) and add your dough. Break it apart into 12 equal-sized pieces.
Break a small portion off of each dough ball and set it aside- these extra pieces are going to be flattened out and used to cover the tops of the mini pies, so they can be small.
Add each of your 12 dough balls to a muffin tin, then use your hands to press the dough down and onto the sides. It's okay if it feels thin, it is pie crust after all.
Preheat your oven to 400 degrees F while you prep the chicken mixture.
Shred or dice up one cup of pre-cooked chicken, then add other ingredients.
Add a spoonful of the mixture into each mini pie crust until all of the mixture has been used (it should be the perfect amount for 12).
Use a fork to poke holes in the tops of the mini pies. Whisk up an egg in a small bowl and brush the tops of the mini pies to help create a golden color (you can skip this if necessary).
Bake at 400 degrees F for 12 minutes.
Let cool for a few minutes before removing. Enjoy warm or save leftovers to reheat throughout the week!