1. Preheat oven to 425F.
2. Place 2 cups of flour, baking powder, and salt in the bowl of your stand mixer. With the mixer on low and the paddle attachment in place, add the butter and mix, until the butter is crumbly and mixed with the flour –about the size of a pea.
3. In a measuring cup, combine cold milk and the extra large egg and beat to combine with a fork. Add the cold milk and egg mixture into the butter and flour, and mix until the flour is moist. Add the grated cheddar and pepperoni pieces into the bowl and mix until roughly combined.
4. Dump dough onto a generously floured counter and knead, with your hands, until the dough is cohesive. Flatten dough with your hands and roll it out to nearly an inch thick (about 10×5 inches). Either with a biscuit cutter or with a sharp knife, cut dough into 8-10 large biscuits. Piece together any leftover dough and repeat. Transfer each biscuit onto a parchment lined sheet pan.
5. For golden, shiny tops, brush the tops with egg wash (1 egg + milk above). Sprinkle additional shredded cheddar on top, and bake for 20-25 minutes until the tops are browned and the biscuits are cooked through.

Serve hot or room temperature with a side of marinara sauce.