Preheat oven to 375 deg F. Line cookie sheet with parchment. Combine first 5 ingredients in processor. Add butter and cut in until mixture resembles fine meal. Transfer to large bowl. Mix in oats and currants. Add 10 tablespoons buttermilk and mix just until dough comes togeterh, adding more buttermilk by tablespoons if dry. Turn dough out onto floured surface. Pat into 1-inch thick round. Cut out rounds using 3 inch cookie cutter. Gather scaraps; pat into 1-inch thick round. Cut out more scones. Transfer scones to prepared cookie sheet, spacing 3 inches apart (scones will spread during baking). Brush generously with egg glaze. Bake scones until brown, about 30 minutes. Cool slightly on rack. Serve warm.