PRE-HEAT OVEN TO 400° F (205° C).
SET UP a half sheet pan and a quarter sheet pan, both lined with parchment paper. Double-pan both. Using 2 pans stacked together will prevent the bottoms of the shortcakes from getting too brown.
SIFT the flour, sugar, baking powder, and salt into a large bowl and whisk to blend.
SCATTER the cold butter cubes over the flour.
RUB in the butter with your hands until you have a mealy texture with only small pieces of butter remaining.
ADD the cream and sieved egg yolks and mix in with a large rubber spatula.
PRESS the dough together in the bowl, then turn it out onto a floured counter.
KNEAD by continuing to press the dough together, then into a rectangle. Fold in half. Rotate dough and press out again into a rectangle and then in half. Repeat 2 more times. Doing this will yield a very smooth dough.
ROLL out the dough into a 7 1/2" x 10" (19 cm x 25.4 cm) rectangle on floured parchment paper; the dough will be about 1" (2.5 cm) thick. Lift the paper with the dough onto a quarter sheet pan and chill in the refrigerator about an hour, or until firm, before cutting the rounds. The shortcakes hold their shape better in the oven when you follow this step of cutting the rounds when the dough is cold.
CUT 12 rounds with a 2 1/2" (6.5 cm) cutter and arrange on the doubled half sheet pans. Press scraps together and re-roll to 1" (2.5 cm) thick and cut out 3 more shortcakes. With the dough that is left, cut out one more shortcake for a total of 16. Place the last 4 on the doubled quarter sheet pans.
BRUSH tops with heavy cream and sprinkle generously with sparkling sugar.
BAKE at 400° F (205° C) for about 20 minutes until light golden brown. The internal temperature should be 209° F (98° C).
COOL on pan.
TO SERVE: Split in half with serrated bread knife. Place bottom halves on plates and top with fresh strawberries, quartered and tossed with a little superfine sugar (Or: I like to toss the berries in Strawberry Coulis, allowing some of the berries and coulis to drip down the sides and fall onto the plates.) Add a dollop of whipped cream and a few more strawberries and coulis. Top with the other half of the shortcakes. Enjoy!
OPTION - EGG YOLKS COOKED SEPARATELY: 1) Crack eggs, being careful not to break the yolks. Separate, saving the egg whites in a separate container for another purpose. 2) Place each yolk into a separate ramekin and slide into a sauce pan of simmering water (3 cups / 720g) and 1 Tablespoon (15g) cider vinegar. 3) Poach for 5 minutes in the simmering water. 4) Lift out with a slotted spoon and let drain and cool on paper towels. Remove any cooked white that remains on the yolks. 5) Press through a fine mesh strainer.