Preheat the oven to 350°F.
In a small saucepan, warm the milk and 2 teaspoons butter together over medium-low heat. With an electric mixer fitted with a wire whip, beat the eggs and 1 cup of the sugar on medium-high speed until the mixture is pale yellow and thick, and has tripled in volume, about 8 minutes. With the mixer on low, beat in the warm milk mixture.
Sift the flour, baking powder, and salt into a medium-size mixing bowl. Fold the flour mixture into the egg mixture and blend thoroughly until smooth. Add the vanilla and mix gently.
Grease a 17 X 12-inch baking pan or jelly roll pan with 2 teaspoons butter. Sprinkle evenly with the remaining 2 tablespoons sugar. Pour the batter into the pan, spreading it evenly. Bake until the cake springs back when touched, about 15 minutes. Cool for about 2 minutes, then gently flip it out onto a large wire rack or a large sheet of parchment paper. Let cool completely.
Yield: 1 sponge cake