Cynthia’s Lemon Squares (from the Mitford book series)

Preheat the oven to 350 degrees. Coat a 9x13-inch baking pan with nonstick cooking spray. Place the flour, 1/2 cup of the confectioners’ sugar, 1 cup of the butter, the vanilla, and 1/4 teaspoon salt in the bowl of an electric mixer and mix on medium speed until combined. Pat the batter into the pan and bake for 18 minutes, or until a light gold color. Melt the remaining 2 tablespoons butter in a small saucepan over low heat. Set aside to cool slightly.

Meanwhile, in the bowl of an electric mixer, combine the granulated sugar and cornstarch. Add the eggs, one at a time, beating well after each addition. Add the lemon zest, lemon juice, 1/8 teaspoon salt, and the melted butter and beat well. Pour the lemon mixture over the crust and bake for another 20 to 25 minutes, or until set. Let cool completely, then sift 2 to 4 tablespoons of confectioners’ sugar over the lemon squares. Chill and cut into squares.

Source: Jan Karon's Mitford Cookbook & Kitchen Reader