Preheat your oven to 400 degrees Fahrenheit. In the bowl of a stand mixer fitted with the paddle attachment, mix together the flour, baking powder, salt, and black pepper. While the mixer is running, add the cubes of butter one at a time. Once the mixture reaches a meal-like consistency, add the grated cheese.
Add the green onions, bacon, jalapenos, and the buttermilk. Mix together with a large spoon until everything just comes together.
Lightly flour a surface and place the dough on it. If you need to, gently knead once or twice. Pat into about a 9" circle. Cut into 8 wedges.
Place the wedges on a baking sheet. Whisk together the egg and water, and brush the surfaces. Bake for about 20 minutes, or until golden brown and set in center.