Step 1: Preheat and Prep

• Preheat your oven to 400°F (200°C).
• Position oven racks in the top and bottom thirds of the oven.
• Line two large rimmed baking sheets with parchment paper.

Tip: Parchment paper ensures easy release and prevents sticking.

Step 2: Make the Cookie Dough

• In the bowl of a stand mixer fitted with a paddle attachment, beat ⅓ cup unsalted butter, 1 teaspoon vanilla extract, 1 teaspoon baking powder, and ½ teaspoon kosher salt on medium-high speed until creamy, about 3 minutes, scraping down the sides as needed.
• Add ½ cup white sugar and beat on medium-high until smooth, about 1 minute.
• Add 1 large egg and beat on low until just combined, scraping down the sides.
• Alternately add 1 ½ cups all-purpose flour and ⅓ cup whole milk on low speed, starting and ending with flour (flour, milk, flour, milk, flour), mixing until just combined.

Tip: Avoid overmixing to keep the cookies soft and cakey.

Step 3: Shape and Bake the Cookies

• Drop slightly rounded tablespoons of dough (about 1 ½ tablespoons each) 2 inches apart onto the prepared baking sheets.
• With floured hands, roll each portion into a ball, then gently flatten to a 1 ½-inch wide circle.
• Bake, rotating pans halfway through, until the bottoms are golden brown, about 10 minutes.
• Transfer pans to wire racks and let cookies cool completely on the pans, about 30 minutes.

Tip: Flatten cookies evenly to ensure uniform size for icing.

Step 4: Make the Icing

• Bring 1 inch of water to a boil in a small saucepan over medium-high heat, then reduce to medium.
• In a medium heat-proof bowl, combine 1 ½ cups semisweet chocolate chips, ½ cup heavy whipping cream, 2 tablespoons light corn syrup, and 1 ½ teaspoons vanilla extract.
• Place the bowl over the simmering water (ensuring it doesn’t touch the water) and whisk constantly until the chocolate melts and the mixture is smooth, about 5 minutes.
• Remove from heat and whisk in 1 cup plus 2 tablespoons sifted confectioners’ sugar and ¼ teaspoon kosher salt until smooth and thickened, about 2 minutes.

Tip: If you don’t have a double boiler, use a heat-proof bowl over a saucepan, ensuring the bowl fits snugly without touching the water.

Step 5: Ice the Cookies

• Dip the flat (bottom) side of each cooled cookie into the warm icing, coating generously.
• Place cookies chocolate-side up on the baking sheets and let cool slightly at room temperature, about 10 minutes.
• Spread remaining icing evenly over the chocolate-dipped tops (about 1 tablespoon per cookie) for a thick layer.
• Let cookies sit at room temperature until the icing is completely set, about 1 ½ to 2 hours.

Tip: Work quickly with the warm icing to ensure it spreads smoothly; reheat gently if it starts to thicken.

Step 6: Serve

• Serve once the icing is set, or store for later enjoyment.

Tip: For a polished look, smooth the icing with a small offset spatula before it sets.