Preheat the oven to 350 degrees F. Line a 9-by-13-inch baking dish with foil, leaving a 2-inch overhang on 2 sides; coat with cooking spray.
Whisk the flour, nutmeg and salt in a medium bowl. Whisk the melted butter, granulated sugar, eggs, egg yolks, brandy and vanilla in a large bowl until smooth. Whisk in the flour mixture until smooth. Spread the batter in the prepared baking dish. Bake until the top is shiny and slightly cracked, about 40 minutes. Let cool completely in the pan.
Lift the bars out of the pan using the foil overhang; dust with confectioners' sugar and sprinkle with nutmeg. Slice into 1 1/2-inch squares.