Cranberry Shortbread

Preheat oven to 350. Line an 8x8x2-inch pan with parchment, leaving a 2-inch overhang on two opposite sides. Whisk flour, ¼ cup sugar and salt in a medium bowl. Using your fingertips, rub butter into dry ingredients until mixture resembles coarse meal.

Transfer to prepared pan; press evenly onto bottom of pan (using the bottom of a flat measuring cup works well). Prick dough all over with a fork.

Bake shortbread until cooked through and pale golden, 25-30 minutes. Transfer to a wire rack. Let cool completely in pan. (Shortbread can be made three days ahead. Cover pan tightly with plastic wrap and store at room temperature.)

Bring remaining ½ cup sugar, 1½ cups cranberries and grapefruit juice to a simmer in a small saucepan and cook, stirring occasionally, until cranberries burst and mixture is syrupy, about 8 minutes. Stir in remaining cranberries and cook until skins begin to split, about 3 minutes. Let cool. (Cranberry topping can be made three days ahead. Cover and chill.)

Spread cooled cranberry topping over shortbread. Scatter grapefruit zest over. Using paper overhang, lift shortbread from pan and transfer to a cutting board. Cut shortbread into squares or rectangles.