Preheat oven to 425. Spray baking sheet with Pam Spray.

In a large mixing bowl, whisk together bread flour, salt, and baking powder until thoroughly combined. Beat in the butter, buttermilk, and confectioners' sugar to make a dough

Gently fold in the onion and Cheddar cheese.

Divide dough in half, and shape each half into a ball. Place the loaves onto the prepared baking sheet, and gently flatten to about 2 inches thick. Dust each loaf with flour.