1½cupsall-purpose flour or unbleached cake flourspooned and leveled
3large egg yolksat room temperature
5large egg whitesat room temperature
For the Soaking Mixture
112-ounce can evaporated milk
114-ounce can sweetened condensed milk
½cup plus 1 tablespoonheavy cream
For the Glaze
113-ounce can dulce de leche
Preheat the oven to 325 degrees.
In the bowl of an electric mixer fitted with the paddle attachment, combine the flour, 3/4 cup of the sugar, and baking powder. Mix on low speed for 1 minute to combine. Do not over-mix.
In a medium bowl, whisk the egg yolks to break them up. Whisk in the oil, water and vanilla, one at a time. Add this mixture to the flour mixture and beat with the paddle on medium speed for exactly one minute to aerate it slightly (it's very important not to overmix). Scrape down the sides of the bowl with a rubber spatula and beat for just a few seconds more.
In a clean, dry mixing bowl combine the egg whites and salt. Place on the mixer with the whisk attachment (or you can use a hand held mixer with beaters) and whip the egg whites on medium speed until they are white, foamy and beginning to hold a very soft peak. Increase the speed to medium high and add the remaining 1/4 cup sugar in a slow stream. Continue whipping the egg whites until they are shiny and hold stiff peaks.
With a large rubber spatula, fold the egg whites into the batter until just combined. Be very careful not to over-mix. Scrape the batter into the ungreased pan and smooth the top. Bake the cake for about 40 minutes, or until it is set in the middle and golden. Let the cake settle on the stovetop or a rack for 1-2 minutes, then invert four glasses onto the countertop and invert the cake pan onto them, positioning one in each corner of the pan. (A chiffon cake needs to hang upside down to cool or it may collapse and fall.)
Once the cake has cooled, flip it over and run a sharp, thin-bladed knife around the edge of the pan to loosen the cake from the sides. Poke holes in the cake with a skewer or point of a small, sharp knife at 1/2-inch intervals.
Prepare the soaking liquid: in a large bowl, whisk together the evaporated milk, sweetened condensed milk, and heavy cream. Slowly pour the soaking liquid over the cake. Let it sit for a few minutes to absorb. If it's slow to absorb, run a knife around the edges of the cake again and poke a few more holes. Place the cake in the refrigerator to chill for at least 8 hours or overnight.
Once the cake has chilled, make the glaze: in a medium microwave-safe bowl, combine the dulce de leche, rum and water. (Note: If you want a really boozy cake, change the proportions in the glaze to 3 tablespoons water and 2 tablespoons rum). Heat for 30 seconds in the microwave, then whisk to combine. Let the mixture cool to room temperature, then spread over cake. Place the cake back in the refrigerator until ready to serve. Serve with fresh fruit, if desired.
Slightly adapted from: Once Upon a Chef You’ll need one 9 x 13 x 2-inch glass pan, ungreased, plus 4 cups or glasses for inverting the cake pan after baking.