Prepare a large baking sheet with parchment paper and set aside.
Whisk together the flour, sugar, baking powder, and salt in a large bowl.
With a pastry cutter or using your hands, cut in the butter until almost fully incorporated into the flour mixture, then mix in the roasted garlic, parmesan, and rosemary.
In a separate bowl, whisk together the milk and egg.
Pour the wet ingredients over the dry, mixing with a spatula until just barely combined. Your mixture should be rough at this stage.
Move the dough to a floured surface and gently knead the dough for a few minutes into a rough ball.
Form the dough into a flattened circle and cut 6-8 wedges, placing them slightly apart on your prepared baking sheet.
Chill the scones in the fridge and preheat the oven to 400ºF if you've turned it off.
Brush the tops of the scones lightly with milk and sprinkle with extra parmesan, rosemary, and salt if desired.
Bake for 20 minutes or until golden brown, risen slightly, and parmesan is crisp.