Preheat oven to 425 degrees F. Line a baking sheet with parchment paper or a silicone baking liner; set aside.

Place the diced rhubarb in a small bowl and toss with 3 tablespoons of the sugar; set aside.

Place the remaining sugar in a large bowl. Add the ground vanilla bean seeds into the sugar and mix until it is evenly distributed. (If using vanilla extract, add it into the heavy cream) Add the flour, baking powder and salt to the bowl and whisk to combine.

Add the cubed butter and, using a pastry blender or two knives, cut the butter into the flour mixture until it is the texture of coarse sand and there are no pieces of butter larger than the size of a pea remaining. Stir the rhubarb and ginger into the mixture, making sure that everything is evenly coated in flour.

Pour the heavy cream into the flour mixture and, using a wooden spoon, gently stir until all of the cream has been absorbed. Turn the dough out onto a lightly floured surface and gently knead a few times to bring the dough together.

Divide the dough in two and pat each into a 7-inch circle. Cut six triangles out of each circle and place on the prepared baking sheet. Sprinkle with additional granulated sugar.

Bake until the scones are golden brown, about 18 to 22 minutes.

Cool on the baking sheet for 15 minutes, then transfer to a wire rack to cool. Serve warm or at room temperature. Store the scones in an airtight container at room temperature for up to 3 days.