Super flaky biscuits

Time: 1.5 hrs
Yield: 9-15 biscuits (depending on size of biscuit cutter)
What's the difference between super-flaky biscuits and flaky-enough biscuits? How we incorporate the butter! We are going to do a little laminating (aka adding butter between layers of dough) here.
Ingredients:
AP flour: 177g
Whole wheat flour: 45g
Discard: 160
Baking powder: 2 tbsp
Salt: 1 tsp, 6 g
Dried thyme: 2 tsp
Cold unsalted butter: 113g, 1 stick, grated
Buttermilk, cold: 165g
Milk: for brushing tops of biscuits
Grate 1 stick of butter on the large setting. You can use the grating setting on your food processor if you don't want to grate by hand. Transfer to tupperware and freeze for at least 30 min.
Preheat the oven to 450F. You will reduce the temperature to 425 when you put biscuits in the oven.
Combine flours, baking powder, salt, and dry thyme in large bowl.
Add 1/3 of cold grated butter. Put rest of butter back in fridge. Mix so butter is dispersed.
Make a well in the center of the mix. Pour in discard and buttermilk.
Mix until just combined - do not overwork.
Transfer to well-floured countertop. Pat or roll into a 1-in rectangular piece.
Sprinkle butter in the center of the dough (see pic below). Fold one side over center. Then sprinkle butter on top of the side you just folded over. Fold the other side over the butter. When you finish, your dough should be folded like a letter. Pat or roll down into rectangle and repeat 2 more times.
Roll into a rectangle that is roughly 3/4 to 1-in in thickness. Then cut out biscuits with biscuit cutter. NOTE: DO NOT TWIST - biscuits rise better when you firmly press down.
Transfer to baking pan of choice. Brush tops of biscuits with milk.
Transfer pan to oven. Reduce temp to 425F. Bake for 20-22 min, or until tops are golden brown.