Preheat the oven to
350ºF with oven rack in the middle. Butter a 10- by 15-inch
jelly roll or sheet pan.
Place 4 tablespoons
(1/4 cup) butter in a small saucepan over moderate heat. Melt
and cook until butter stops foaming, smells toasty, and
begins to brown, approximately 10 minutes.
NOTE: The browner the butter, the
deeper the flavor, but don’t let it blacken or burn.
Set aside to cool to room temperature.
Place the remaining
3/4 cup butter in a large bowl. Using an electric mixer or wooden
spoon, beat until creamy. Add the granulated sugar, brown
sugar, and salt; continue to beat until light and fluffy. Add the egg yolk,
vanilla extract, and the cooled browned butter; mix to combine. Then add
flour, 1 cup at a time, and stir with a wooden spoon to
combine. Refrigerate the batter for approximately 20 to 30
minutes.
Divide
chilled dough into
eight (8) rough portions and
arrange them evenly in the pan. Press dough down into an even
layer to completely fill the jelly roll pan.
In a small bowl, beat
the egg white with a pinch of salt. Brush mixture evenly
over the dough. Sprinkle chopped hazelnuts over the top; press down
lightly.
In another small bowl, combine 2 tablespoons sugar with
the cinnamon and nutmeg, and sprinkle over the top of the nuts; then sprinkle sea salt over the top.
Bake, rotating the pan
once halfway through baking, until golden brown and crisp,
about 25 minutes. Remove from oven and let cool for 10 minutes; cut into 1- to 2-inch
squares or diamonds. Transfer to a cooling rack.
Melt the chocolate in
a metal bowl set over a pan of simmering water. Using a very
small tipped pastry bag or the tines of a fork, drizzle the
chocolate over the tops of the shortbreads.
Makes 3 to 4 dozen
cookies.
