Twice-Baked Shortbread (adapted slightly from the Smitten Kitchen)
12 Tb (1 1/2 sticks) unsalted butter, melted and still warm
5 Tb granulated sugar
1 tsp pure vanilla extract or the scrapings from half a vanilla bean
1/4 tsp salt (I recommend heaping if you want more of a salted butter taste, like me)
1/4 tsp freshly grated nutmeg
1 1/2 cups (6.75 ounces) all-purpose flour
Turbinado, Demerara or granulated sugar for sprinkling
You'll need: a baking pan with a removable bottom, such as a 9 1/2-inch round or a 4 by 14-inch rectangular fluted tart pan, or a one-piece 8-inch square pan. If using a pan with a removable bottom, grease the pan; if using the one-piece 8-inch pan, line it with aluminum foil, leaving an overhang on two opposite sides.
In a medium bowl, whisk together the melted butter with the sugar, vanilla of your choice, and salt. Add the flour, nutmeg and mix until just incorporated. Spread the dough evenly in the pan with your fingers. Let rest for at least 2 hours, or overnight, on the counter.
Preheat the oven to 300 degrees, and position a rack in the lower third of the oven.
Lightly sprinkle the surface of the shortbread with the coarse sugar you chose. Bake the shortbread for 45 minutes.
Remove the pan from the oven, leaving the oven on. Let the shortbread cool for 10 minutes.
Remove the shortbread from the pan, being very, very gentle with it. Use a thin sharp knife to cut it into oblong “fingers”, wedges, or squares. Place the pieces slightly apart on a parchment-lined baking sheet and return to the oven for 15 minutes. Cool on a rack.