Chiffon Cake:

Separate 4 eggs into yolks and whites, and let them come to room temperature (about 30 min). Then preheat the oven to 350 degrees Fahrenheit.

Line a jelly roll pan (10.5" x 15.5") with parchment paper. Do not grease the pan or the parchment paper.

In a large bowl, sift together 1 cup of cake flour, 2 tsp of baking powder, 1/4 cup of sugar, and 1/2 teaspoon of salt.

Add in 4 egg yolks, 1/3 cup of vegetable oil, 1/2 cup water, 1/4 tsp finely grated orange zest, and 1 teaspoon of vanilla extract. Beat this together with an electric mixer just until smooth and well blended.

In a separate bowl glass or stainless-steel mixing bowl, add in the 4 room temperature egg whites and 1/2 tsp cream of tartar, and beat on low speed until it's frothy. Then increase to medium speed, and very slowly add in 1/3 cups sugar while continuing to beat. When all the sugar has been added, increase to high speed, and continue beating until you see stiff glossy.

One-third at a time, very gently fold in this meringue mixture into the chiffon batter until it is well combined. Pour this batter into the prepared jelly roll pan, and smooth the top with the spatula.

Bake for about 18 to 20 minutes or until the surface springs back when gently pressed.

Dust the cake with some confectioner's sugar to prevent sticking. Place a rectangular piece of parchment paper that's bigger than the cake on top, and invert the cake onto the parchment paper and slowly remove the baking pan so that parchment paper is on top. Then slowly peel off the parchment paper the cake was baked with.

While the cake is still warm, dust additional confectioner's sugar onto this side of the cake (to prevent cake from sticking), and
roll the cake with the parchment paper along the short 10.5-inch side, place with the seam side down so it doesn't unroll, and let it cool to room temperature on a wire rack.

Mango Swiss Buttercream:

Take 2 cups of unsalted butter, cut it into 1-inch cubes, and let it come to room temperature.

In a large heat-proof bowl like glass or stainless steel, add in 5 egg whites, 1 1/2 cups of sugar, and 1 tsp of salt. Whisk together until they are combined.

Set up a double boiler and heat the egg white mixture in a low heat water bath while continuing to whisk, till the sugar is dissolved (when it feels sticky to touch, and you hardly feel the grains of sugar anymore). If you have a thermometer, it needs to reach 160 degrees Fahrenheit.

Take it off the water bath. Using an electric mixer, beat this mixture until glossy and stiff peaks form. Let it cool down completely to room temperature.

When it is back to room temperature, continue beating and slowly add the 2 cups pre-cut room temperature (unsalted) butter one cube at a time. The mixture might start looking curdled, but do not worry, that's just because the butter is too cold and not fully mixed in. Just continue mixing with the electric mixer until it looks smooth.

When the butter is fully mixed in and the frosting looks smooth, add in 2 tsp of vanilla extract and mix it in. Then transfer 1 cup of this frosting into a piping bag fitted with a large star tip. Set this aside at room temperature for making rosettes at the end.

Take 2 mangoes, and slice them so that you get 4 mango halves and 2 seed pieces. Take one of the mango halves, wrap it in plastic wrap and set it aside to use later.

Take the remaining 3 mango halves and 2 seed pieces - slice the 3 mango halves into cubes and place the pieces into a blender. Slice the mango flesh around the 2 seed pieces as much as you can, and place them into the blender as well.

Add in 2 tbsp of granulated sugar and 1/4 cup of water. Blend this very well until it is a smooth mango puree.

Add this mango puree into the remaining Swiss-meringue buttercream frosting

Mix this in with the electric beater until it's smooth. Scrape down the bowl to ensure that everything is mixed in. Let this rest at room temperature until you're ready to use it.

Assembling the Cake:

When the chiffon cake has cooled to room temperature, slowly and carefully unroll the cake.

Spread a thin layer of the Mango Swiss buttercream frosting on the top surface of the cake, about 1/4 inches thick.

Slowly and carefully roll the cake up again, the same direction it was rolled before but this time without the parchment paper rolled into it.

Transfer the roll to your serving dish, with the seam-side down, so it doesn't unroll. Fill the gaps at the ends of the cake with the
Mango frosting. Then cover the outer surface of the cake with a thin layer of frosting, as a crumb coat. Smooth it out with a bench scraper, and let your cake rest in the fridge for 20 minutes for the frosting to harden a bit.

When your crumb coat has hardened a bit, apply a 2nd layer of frosting, about 1/4" thick on the outer surfaces. You can use all the remaining Mango frosting at this point. Smoothen it with a bench scraper. If you have an icing comb, you can create a pattern on the outside surface of the frosting at this point. Let this rest in the fridge for the mango buttercream to firm up a bit.

While 2nd layer of mango frosting is hardening, work on the
mango glaze. Take the remaining half of mango (that was covered in plastic wrap earlier), slice it into cubes, and place
pieces into a blender.

Add in 1/4 cup of water, 2 tbsp of granulated sugar, and 1/2 tsp of cornstarch. Blend this mixture very well until it is a smooth puree.

Pour this mixture into a small skillet or saucepan over medium heat, and bring to a boil. Once it's boiling, turn off the heat, transfer it into a clean bowl, and let this mango glaze cool slightly - about 5 to 10 minutes.

When the mango glaze has cooled down, but still a bit warm so it is runny and not hardened, transfer it into a disposable piping bag or Ziploc bag. Cut at a small hole in one of the corners. Do some practice drizzles on a plate.

When you're confident about your drizzles, take your cake roll
out of the fridge, and drizzle the mango glaze over your cake roll
in a zig-zag, pattern. Try to drizzle the mango with a very quick and confident motion while squeezing the bag of mango glaze pretty hard to get a straight zig-zag pattern, and avoid getting a squiggly drizzle. Set the remaining mango glaze aside.

Take the 1 cup of plain Swiss-meringue buttercream frosting that was saved in the piping bag. Pipe out rosettes on top of the roll, but shape the rosettes in a way that they have a small hollow space in the center. I'm aiming for 6 rosettes here.


Finally, take the bag with mango glaze, and squeeze a little bit of
mango glaze into the small hollow space in the middle of each rosette.

Let it rest for 1 hour at room temperature for the cake to set before serving. Or refrigerate overnight if serving the next day. If refrigerating, let the cake come to room temperature (30 minutes to 1 hour at room temperature, depending on how hot it is) before serving, for frosting to soften again and for the cake to have a more vibrant mango flavor. Enjoy!