2 large eggs, separated, room temperature

½ cup (3 ½ ounces) sugar

4 teaspoons all-purpose flour

½ teaspoon cornstarch

2 tablespoons unsalted butter, softened

2 teaspoons grated lemon zest plus ¼ cup juice (2 lemons)

½ cup whole milk, room temperature

1. Adjust oven rack to lowest position and heat oven to 325 degrees. Place dish towel in bottom of 13 by 9 -inch baking pan. Grease 7 ¼ by 5 ¼-inch baking dish and set on towel. Bring kettle of water to boil.

2. Using hand-held mixer set at medium-low speed, beat egg whites in large bowl until foamy, about 1 minute. Increase speed to medium-high and beat whites to soft, billowy mounds, about 1 minute. Gradually add 6 tablespoons sugar and beat until glossy, stiff peaks form, 2 to 6 minutes; set aside.

3. Whisk flour and cornstarch together in small bowl. Using hand-held mixer set at medium-high speed, beat butter, lemon zest, and remaining 2 tablespoons sugar in medium bowl until pale and fluffy, about 3 minutes, scraping down sides of bowl as needed. Add egg yolks and beat until combined, about 30 seconds. Reduce speed to low and slowly add flour mixture until combined, about 30 seconds. Add milk and lemon juice and beat until just combined.

4. Using rubber spatula, stir one-third of whites into batter, then add remaining whites and gently fold into batter until no white streaks remain. Scrape batter into prepared dish and smooth top. Set pan on oven rack. Taking care not to splash water into dish, pour enough boiling water into pan to reach halfway up sides of dish. Bake cake until surface is golden brown and edges are set (center should jiggle slightly when gently shaken), about 1 hour.

5. Carefully transfer baking dish to wire rack and let cake

cool until warm, about 30 minutes. Serve warm or at room temperature.