Put the COLD butter in a mixing bowl with the dry ingredients and cut it with a pastry cutter until you get coarse crumbs. Now add your milk. Stir to combine. Throw the dough back in the fridge until your filling is ready.
Taco Filling
Brown the ground Beef on medium - high heat. Make sure to break it up as small as possible, this will make the eating experience much better.
While the meat browns, cut your veggies. Again, the smaller these are the better. If you wanted to be efficient about it, you could throw it all in a food processor with the S blade and get the veggies super small, but a knife will work just fine. I cut my veggies for this with a knife :)
Add the veggies to the meat mix and saute until they've cooked down a bit now add the water and seasoning. Stir to combine. You'll want to cook this mixture until the moisture cooks off.
Preheat Oven to 375°F
Assembly
Roll out your chilled dough. I chose to roll my dough out to ½" thickness then used my largest biscuit cutter which is 2.5" wide and then roll my biscuits out more so at the end they were ¼" thick and 4" wide. If you have a cutter or large cup or sharp edged bowl that's at least 4" wide you can just roll your dough to a ¼" thick and cut your shapes from that. I wouldn't try to make these any smaller than with a 4" disc because its hard enough as is to stuff a 4" disc.
Working one at a time, scoop some shredded or sliced cheddar cheese on half of the biscuit disc, then add in the topping. Fold over the top to create a crescent moon shape. Then seal them by pinching the seams closed. You can also seal with the tines of a fork or you can do both because you trust no one and nothing. haha.
Brush the tops with your egg wash and then score lines in the top with a knife to give steam vents, this will help prevent your seams from bursting.
Bake
Bake for 12-14 Mins They will be nice and golden brown on top and browned on the bottom when done. Remove from cookie sheet once they are out of the oven and transfer to a cooling rack or the families plates or your mouth.