In a large bowl sift together the flour, sugar, baking powder and salt.
Using a pastry blender, cut the cold butter into the dry ingredients until the butter is pea sized. (I actually like to use my hands to do this part.)
Stir in the cream until the dough is moistened, but be careful not to over mix it or the scones will be tough.
Then gently mix the chopped rhubarb into the scone dough using your hands.
Lay a sheet of parchment paper onto your counter and lightly dust it with flour.
Press the dough into a ball and transfer it on to the parchment paper floured surface and press it down into a rectangular disk. Then using a rolling pin, roll and flatten the dough to a 1 inch thickness.
Using a knife cut the dough into squares or triangles, or use a biscuit cutter or cookie cutter to make circle shaped scones.
Place the scones onto a baking sheet lined with parchment paper.
Brush the scones with a bit of cream and sprinkle generously with sugar.
Bake for about 10-15 minutes. The scones are done when the bottom edges are slightly brown.
When they are done baking, transfer the scones to a cooling rack.