Makes 2 dozen 3-inch squares
1 cup (2 sticks) unsalted butter, at room temperature
1 1/2 cups sugar
1/2 teaspoon lemon extract (or 1 tablespoon lemon juice–see note)
1 teaspoon pure vanilla extract
1/2 teaspoon salt
2 cups all-purpose flour
1 (21 ounce) can cherry pie filling
Confectioners’ sugar, for dusting
Position a rack to the center of the oven and preheat it to 350 degrees. Grease and flour a half-sheet pan (about 12×17 inches) with a 1-inch rim, or spray it with cooking spray, line it with parchment paper, and lightly spray the parchment, too.
In the bowl of an electric mixer, beat together the butter and sugar until very light and fluffy, about 2 minutes. Beat in the lemon extract, vanilla and salt. Beat in the eggs one at a time. Scrape down the bowl. On the lowest speed, stir in the flour. To avoid overbeating, stop mixing when there’s a few streaks of flour left, and finish stirring the batter by hand.
Scrape the batter onto the sheet pan and smooth it into an even layer. Score the batter into 24 squares with a toothpick (don’t worry about perfectly even squares as the lines will disappear during baking; it’s just to make placing the cherries easier). Place 3 cherries in the center of every square.
Bake until a toothpick comes out clean, about 30 minutes. Cool completely in the pan on a wire rack. Just before serving, cut into 24 squares and dust with powdered sugar. Store any leftovers in an airtight container with layers of waxed paper or parchment for up to 3 days.