Position a rack in the center of the oven; preheat to 425°.
Line a half-sheet pan with parchment paper.
Whisk the milk and 2 eggs together in a small bowl; set aside.
Sift the dry ingredients together in the bowl of a stand mixer.
Add the butter; attach the bowl to the mixer and fit with paddle attachment.
Mix on med-low speed until the mixture looks mealy with some pea-size bits of butter.
Mix in the currants.
Decrease mixer speed to low; add the milk mixture, mixing just until the dough barely comes together.
Turn the dough out onto a well-floured work surface and sprinkle with about 2 tablespoons flour on top.
Knead the dough a few times, just until it doesn't stick to the work surface.
Do not overwork the dough; the surface will be floured, but the inside of the dough should remain on the wet side.
Gently roll out the dough into a 3/4-inch thick round.
Using a 2 1/2 inch fluted biscuit cutter, dipping it into flour between cuts, cut out the scones (cut straight down and do not twist the cutter) and place 1 1/2 inches apart on the prepared half-sheet pan.
To get the most scones out of the dough, cut out the scones close together in concentric circles.
Gather up the dough scraps, knead very lightly, and repeat to cut out more scones.
Brush the tops of the scones lightly with the beaten egg, being sure not to let the egg drip down the sides (which would inhibit a good rise).
Place the scones in the oven and immediately decrease heat to 400°.
Bake until golden brown, about 20 minutes.
Cool on the pan for a few minutes, then serve warm or cool completely.