Pre-heat oven to 400 degrees and line a baking sheet with parchment paper.
In a large bowl, whisk together flour, baking powder, sugar, salt, and pepper.
Cut in chilled butter with a pastry cutter or fork (or your fingers) until butter is in pea-sized pieces. In a small bowl, lightly whisk together 2 of the eggs and the buttermilk add it to the flour mixture with cheddar and jalapeño. Mix together using a wooden spoon until combined.
On a lightly floured surface, knead the dough for about 30 seconds. Pat into a round that's about ¾" thick. Using a biscuit cutter or the top of a drinking glass, cut as many scones as you can from the dough. I got 10 scones with a 2 ½" biscuit cutter. Place scones on prepared baking sheet.
Lightly whisk remaining egg in a small bowl. Brush the tops of scones with egg.
Bake for 17-20 minutes, until scones are turning golden brown. Let cool on pan for a couple minutes before moving to wire racks to cool completely or enjoying warm.