Step 1 In the bowl of a stand mixer fitted with the paddle attachment, or in a bowl using a hand mixer, beat the butter and sugar until creamy. Add the flour and beat into the butter mixture just until fully incorporated.
Step 2 Divide the dough into thirds and shape each third into a 10-inch by 3-inch rectangle on a lightly floured board. Score the rectangle crosswise to make 20 (1/2-inch) bars. Repeat with the remaining rectangles and place onto parchment-lined baking sheets (you may be able to fit 2 rectangles on one sheet, but do not space too closely together as the shortbread will spread a little as it bakes). Chill the dough for 30 minutes. Meanwhile, heat the oven to 350 degrees.
Step 3Remove a tray and bake until the shortbread feels firm to the touch and the edges are just beginning to color, about 20 minutes. Remove the sheet to a rack and cut each bar along the scored lines. Set aside to cool. Repeat until all of the shortbread is baked and cooled. Separate the bars and place onto a parchment-lined baking sheet. Cover and refrigerate until ready to coat with the caramel.