ingredients

• 4 egg yolks
• 4 egg whites, beaten, with a few drops of vinegar, to stiff peaks
• 1/2 liter of warm milk
• 125 grams of unsalted butter, melted, then cooled slightly until just warm
• 140 grams of powdered sugar
• zest of half a lemon
• 112 grams of all-purpose flour
• 1 vanilla bean, cut in half with seeds scraped

method

• Preheat oven to 350 degrees F. Prepare 8-inch square pan by greasing with butter and lining parchment paper that hangs over two sides, greasing the parchment paper as well, for easy removal. Separate egg yolks from whites into two separate bowls.
• Starting with the yolks, add the powdered sugar and scrape vanilla bean seeds into it, then beat with a hand held mixer for about five minutes. Mixture should be very pale and thick, and when you lift the beaters, it should look like a “ribbon” folding over itself.
• Add zest of lemon and mix until incorporated. Pour all of butter into the egg yolk mixture, then mix with electric hand held beater until fully incorporated and mixture starts to thicken slightly again. Gradually add in some of the warm milk, a third of it at a time, mix until incorporated, until all the milk has been added, then sift the flour over the mixture and mix on medium speed, until incorpoarated. Do not over-mix.
• Wash beaters, or use another set of clean beaters, to whip up egg whites to stiff peaks when beaters are lifted from egg whites. Fold into the batter with a spatula, quickly but gently, being careful not to over-mix or deflate the whites. Pour into prepared pan and bake for ten minutes at 350 degrees F, then lower heat to 325 degrees F, without opening door, continuing to bake for 50 minutes more, or until toothpick test comes out clean.
• Cool completely on wire rack, leaving it in its pan, then cover with a plastic wrap and cool in refrigerator for at least 3 hours, or overnight. Unmold and cut into equal pieces, dusting each piece with powdered or confectioner’s sugar, and then, if desired, topping each slice with some whipped cream and frosted green grape.