Preheat oven to 400°F and line a baking sheet with parchment paper or spray with cooking spray.
In a large bowl, whisk flour and 1/4 cup sugar, baking powder and salt. Work in butter with fingertips or a pastry cutter until mixture resembles coarse crumbs. Stir in currants.
In a small bowl, whisk together 2/3 cup cream and egg yolks; stir into flour mixture with a fork until dough comes together in a ball. Knead dough in bowl three times to blend; do not overwork. On a lightly floured surface, pat dough into a 3/4-inch-thick round. Using a 2 1/2- to 3-inch cutter, cut out 5 scones and transfer to prepared baking sheet. Reshape scraps and cut 2 more scones. Brush scones with remaining 1 Tbsp. cream and sprinkle remaining 1 Tbsp. sugar on top.
Bake scones until golden, 15 to 20 minutes. Let cool for 10 minutes before eating.