Remove the lid and sprinkle the 1 tablespoon of baking powder on top of the dough. Break the egg over the dough. Mix both into the dough by hand; use your hands to squish and incorporate the egg. Do not overmix.
Remove the dough from the bowl and roll out into a flat rectangle. Sprinkle the 1 cup of chopped grapes evenly over the dough. Press them lightly into the dough.
Take one edge of the dough and fold it to the center of the rectangle. Take the opposite edge of the dough and fold it over the other folded edge. Repeat for the last two edges of dough. You will create four layers of grapes and dough.
Gently roll out the dough into a rectangle with an 8" - 10" length. If you have side seams open up or holes with petals escaping, gently pinch them closed with your fingers and smooth the dough.
Carefully remove the rectangle of dough to a parchment paper-lined baking tray. Use a pizza cutter to cut the dough into 6-12 squares.
Place in the refrigerator while the oven preheats to help the scones keep their shape. Set the oven to preheat to 400F/204C.
When the oven is ready, brush the scones with the reserved cream and sprinkle with the reserved sugar. Put in the oven to bake for 25 minutes or until golden brown. If your oven runs hot, place a piece of foil over the scones for the last 5 minutes of bake time.
Remove from the oven and allow to cool for at least 10 minutes to set up. You can serve them piping hot from the oven, but be gentle so they don't loose their shape.