Instructions

• In a large bowl or the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter and powdered sugar on medium speed until smooth and creamy, about 2–3 minutes.
• Add the vanilla extract and the salt and mix until evenly incorporated.
• Add the all-purpose flour 1 cup at a time, mixing on low speed and scraping down the bowl between additions, until the flour is fully incorporated and a cohesive dough has formed (you will add a total of 3 cups).
• If the dough is too sticky to roll, cover and chill for 20 minutes, then continue. If it is workable, proceed immediately.
• Divide the dough in half. Place one half between two sheets of parchment paper or wax paper and roll to an even 1/4-inch thickness. Repeat with the second half.
• Place the rolled dough (still between the paper layers) on a baking sheet or tray and chill in the refrigerator for at least 2 hours or up to overnight.
• Preheat the oven to 350°F (177°C). Line baking sheets with parchment paper or silicone baking mats.
• Remove one sheet of chilled dough from the refrigerator and peel off the top piece of parchment. Using a cookie cutter (about 2 inches for the size in the original recipe, or any desired shape/size), cut out cookies. Re-roll scraps and repeat until all dough is used, keeping the dough about 1/4 inch thick.
• Transfer cut cookies to the prepared baking sheets about 1–2 inches apart (these cookies do not spread much).
• Bake 14–18 minutes (time will vary with cookie size and thickness) until the edges just begin to turn golden. Allow cookies to cool on the baking sheet for a few minutes, then transfer to a wire rack to cool completely.
• When cookies are fully cool, turn half of them upside down. Open the can(s) of dulce de leche and spoon it into a piping bag or a resealable plastic bag with a corner snipped off. Pipe or spoon about 1–2 tablespoons of dulce de leche onto each upside-down cookie, then top with a second cookie to form a sandwich.
• Store the assembled cookies in an airtight container for up to 3 days at room temperature, or freeze for up to 1 month. Optional: dust with additional powdered sugar before serving.