Preheat your oven to 375°F (190°C).
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
Add the cold, cubed butter to the dry ingredients. Using a pastry cutter or your fingers, cut the butter into the flour mixture until it resembles coarse crumbs.
In a separate bowl, combine the milk (or water) with the egg, if using.
Pour the wet ingredients into the dry ingredients. Mix until just combined, being careful not to overwork the dough. If using raisins or dried fruit, fold them in now.
Turn the dough out onto a lightly floured surface and gently knead it a few times until it holds together.
Pat the dough into a round or square shape about 1 inch thick. Transfer to a baking sheet lined with parchment paper or a greased baking dish.
Bake in the preheated oven for 20-25 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Allow the bannock to cool slightly before slicing. Serve warm or at room temperature.
Enjoy your meal!