Whisk 3 cups flour, 1 teaspoon baking powder, and 1/2 teaspoon salt together in a bowl.

Cream 1 cup butter and 1 cup sugar together for 3 minutes, until fluffy.

Beat in the egg and vanilla.

Mix in the dry ingredients until the dough just comes together.

Divide the dough in half, wrap each half, and chill for 1 hour, until firm enough to roll without sticking.

Preheat the oven to 350°F and line baking sheets with parchment.

Roll the dough 1/4 inch thick and cut hearts with a 2 to 2.5 inch cutter, placing them 2 inches apart on the sheets.

Bake for 9 to 11 minutes, until the edges just turn golden and the centers are still pale.

Cool on the sheet for 5 minutes, then on a rack for 15 minutes more.

Whisk the powdered sugar with 3 to 4 tablespoons milk until it ribbons off the whisk and disappears back into the bowl within 10 seconds; split the icing in half and tint one half pink.

Outline and flood half the hearts in pink and leave the rest white, then let the icing set uncovered for 1 to 2 hours, until matte and firm to the touch.

Arrange 9 cookies, alternating pink and white hearts, into the 3x3 grid of a tic-tac-toe printed bakery box like a tied game.

Close the lid and secure with a ribbon; the dough makes enough for 3 boxed sets of 9.