ArcaMax

1/4 teaspoon baking soda

1 large egg

2 tablespoons water

2 teaspoons vanilla extract

1/2 cup (3 ounces) mini semisweet chocolate chips, plus 1 cup for optional garnish

3 pints ice cream

1. Adjust oven rack to middle position and heat oven to 325 F. Melt butter in a 10-inch skillet over medium-high heat. Cook, stirring and scraping skillet constantly with a rubber spatula, until milk solids are dark golden brown and butter has nutty aroma, 1 to 3 minutes. Immediately transfer to a heatproof large bowl. Whisk in sugar and salt until fully incorporated and let mixture cool for 10 minutes. Meanwhile, line two rimmed baking sheets with parchment paper. Stir flour and baking soda together in a second bowl; set aside.

2. Add egg, water and vanilla to the browned butter mixture and whisk until smooth, about 30 seconds. Using a rubber spatula, stir in flour mixture until combined. Stir in 1/2 cup chocolate chips. (The dough will be very soft.)

3. Using a #60 scoop or 1-tablespoon measure, evenly space 12 mounds of dough on each prepared sheet. Bake cookies, 1 sheet at a time, until puffed and golden brown, 9 to 12 minutes, rotating sheet halfway through baking. Let cookies cool on the sheet for 5 minutes, then transfer to a wire rack and let cool completely, about 45 minutes. Place one sheet, still lined with parchment, in freezer.

4. Place 4 cookies upside down on the counter. Quickly deposit 2-inch-tall, 2-inch-wide scoop of ice cream in center of each cookie. Place 1 cookie from the wire rack right side up on top of each scoop. Gently press and twist each sandwich between your hands until the ice cream spreads to edges of the cookies (this doesn't have to be perfect; ice cream can be neatened after chilling). Transfer sandwiches to the sheet in freezer. Repeat with remaining cookies and remaining ice cream. Place 1 cup chocolate chips, if using, in a shallow bowl or pie plate.

5. Remove first 4 sandwiches from freezer. Working with 1 sandwich at a time, hold sandwiches over bowl of chocolate chips and gently press chocolate chips into sides of sandwiches with your other hand, neatening ice cream if necessary. Return garnished sandwiches to the freezer and repeat with the remaining 8 sandwiches in two batches. Freeze sandwiches for at least 8 hours before serving. (Sandwiches can be individually wrapped tightly in plastic wrap, transferred to zipper-lock bag, and frozen for up to two months.)

Recipe notes: These sandwiches should be made at least 8 hours before serving. For the best results, weigh the flour and sugar for the cookies. We prefer the deeper flavor of dark brown sugar here, but light brown sugar will also work. Use your favorite ice cream. If using a premium ice cream such as Ben & Jerry’s or Häagen-Dazs, which is likely to be harder than a less-premium brand when frozen, let the ice cream soften slightly in the refrigerator before scooping. We like these sandwiches with chocolate chips pressed into the sides, but the garnish is optional.

(For 25 years, confident cooks in the know have relied on America’s Test Kitchen for rigorously tested recipes developed by professional test cooks and vetted by 60,000 at-home recipe testers. See more online at www.americastestkitchen.com/TCA.)