Ingredients :
1-1/2 teaspoons vanilla extract
3/4 teaspoon cream of tartar
9 large egg whites, room temperature
1 cup plus 2 tablespoons sugar
3/4 cup cake flour
1 tablespoon of icing sugar
filling:
1 cup of sugar
3 tablespoons cornstarch
1 cup of water
1 large egg, lightly beaten
1/4 cup lemon juice
1 tablespoon grated lemon zest
Yellow food coloring, optional
Extra confectioners sugar

instructions :
Line a 15x10x1-in. mold with waxed paper; lightly coat paper with cooking spray.
Preheat oven to 350°. Add vanilla and cream of tartar to egg whites; beat at medium speed until soft peaks form. Gradually add the sugar, 2 tbsp. at a time, on high until glossy, stiff peaks form and the sugar is dissolved. Stir in the flour, about 1/4 cup at a time.
Gently spread the dough into the prepared pan. Bake until cake springs back when lightly touched, 15 to 20 minutes. Cool for 5 minutes.
Turn the cake onto a towel dusted with 1 tablespoon of icing sugar. Carefully peel off the wax paper. Roll the cake up like a rolled towel, starting at one small side. Cool completely on a rack.
In a large saucepan, combine sugar and cornstarch; stir in water until smooth. Cook and stir over medium-high heat until thickened and bubbling. Lower the temperature; cook and stir 2 minutes. Remove from fire. Stir a small amount of hot mixture into egg; return everything to the saucepan, stirring constantly. Bring to a gentle boil; cook and stir 2 minutes.
Remove from fire. Gently stir in the lemon juice, zest and, if desired, food coloring. Cool to room temperature without stirring.
Unroll the cake; spread filling to within 1/2 inch of edges. Ride again. Place seam side down on a serving plate; sprinkle with additional confectioners’ sugar.