Step 1: Prepare Dry Ingredients - Whisk together the flour, sugar, baking powder, garlic powder, salt, and pepper in a large bowl until evenly mixed. Stir in the chopped chives and shredded cheese.
Step 2: Incorporate Butter - Grate the frozen butter into your dry mixture. Combine until you achieve a crumbly consistency resembling pea-sized crumbs.
Step 3: Mix Wet Ingredients - In a separate bowl, whisk together buttermilk and the egg yolk. Pour this mixture over your flour blend along with the chopped chicken ham and gently mix until everything clumps together.
Step 4: Shape Dough - Transfer your dough onto a lightly floured work surface and shape it into a ball. Press it into an 8-inch disc and cut into wedges.
Step 5: Chill and Bake - Brush the shaped scones with egg wash and refrigerate for at least 15 minutes. Preheat your oven to 400°F (204°C) and bake until golden brown, about 22-25 minutes.