Blackberry and Walnut Scones with Vanilla Bean Lemon Curd

Name: Blackberry and Walnut Scones with Vanilla Bean Lemon Curd
Ingredients: For the Scones; 2 cups all-purpose flour; 1/3 cup sugar; 1 teaspoon baking powder; 1/4 teaspoon baking soda; 1/2 teaspoon salt; 1/2 cup (1 stick) unsalted butter, cut into chunks and frozen; 1/2 cup sour cream; 1 large egg; 3 teaspoons water; 1 (6-ounce) container fresh blackberries; 1 cup walnuts, coarsely chopped; For the Vanilla Bean Lemon Curd; 6 tablespoons unsalted butter, softened; 1 cup sugar; 2 large eggs; 2 large egg yolks; 1 vanilla bean, seeds scraped; 2/3 cup fresh lemon juice (about 4-5 lemons)