Start by washing the fresh rhubarb thoroughly to remove any dirt. Finely chop the rhubarb into small, even pieces.

In a large mixing bowl, combine 2 cups of all-purpose flour, 1 tablespoon of baking powder, and 1/3 cup of sugar. Whisk together until well blended.

Add 1/2 cup of cold, cubed unsalted butter to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the mixture until it resembles coarse crumbs.

Carefully fold in the chopped rhubarb pieces into the butter-flour mix, stirring until the rhubarb is evenly distributed among the dry ingredients.

In a separate bowl, whisk together 3/4 cup of heavy cream and 1 teaspoon of vanilla extract. Gradually add this mixture to the dry ingredients, stirring until just combined.

Turn the dough onto a floured surface and gently knead it a few times until it holds together. Shape the dough into a 1-inch thick disk, wrap in plastic wrap, and chill in the refrigerator for about 15 minutes.

Once chilled, remove the dough and slice it into wedges, creating about 8 scones. Place each wedge on a parchment-lined baking sheet, spaced about 2 inches apart.

Preheat your oven to 400°F (200°C). Brush the tops of the scones with a beaten egg if desired. Bake for 15-18 minutes or until risen and golden-brown.

Allow the scones to cool slightly on a wire rack. Dust with powdered sugar or serve warm with clotted cream and fruit preserves.