100grcake flour plus more to coat purple sweet potato pieces
¼tspsalt
MERINGUE:
5egg whites room temperature
½tspcream of tartar
70grsugar
Instructions
Make sure your chiffon cake pan does not have a non-stick coating or your cake will not rise. The cake needs to cling to the side of the pan to rise tall
Preheat your oven to 330 F (165 C) for a conventional oven. If you have a convection oven, I suggest lowering the temperature by 20 F (15 C)
STEAM THE PURPLE SWEET POTATOES:
Peel the skin off sweet potatoes and cut into tiny pieces. Steam over high heat for about 5-7 minutes. Remove the amount required in the recipe and cut into tiny pieces and some for mashing. Mash the potatoes while they are hot. Set aside
Separate the egg yolks from the whites while they are still cold because they are easier to separate when they are cold. Then let them sit out for 20-30 minutes at room temperature. The meringue whips better at room temperature
PREPARE THE CAKE BATTER:
Whisk the egg with mashed sweet potatoes, sugar and cooking oil, ube extract/food coloring, then add coconut milk. Sift in the cake flour and salt
WHIPPING THE MERINGUE:
Place the egg whites in a clean bowl. You will have trouble whipping your meringue if there's a trace of grease in your utensils or bowls. Beat the egg whites on medium speed (speed 6 on KA) until frothy, add cream of tartar/lemon juice/vinegar and whip until it turns whitish, about 1 minute. Gradually add the sugar as you beat, about 1 minute apart. Continue whipping on medium speed until you reach a stiff peak with a slight bent on the tip when you lift the meringue up. Then turn the speed to lowest and whip for 1 minute to smooth out large air bubbles
FOLDING THE MERINGUE:
Gently fold 1/3 of the meringue into the thick batter using a whisk. Continue on with second 1/3 of the meringue again to mix. Continue to do this until you are done with the meringue and switch to a rubber spatula. Swipe down and fold over motion again to make sure we are combining the batter and the meringue. Sometimes some batter at the bottom of the bowl didn't get mixed with the meringue
Coat the tiny pieces of sweet potatoes with about 2-3 teaspoons of cake flour. Shake off excess. This will help to prevent the potatoes from sinking to the bottom during baking
Add the coated sweet potatoes into the batter and gently swipe down and fold over again using a rubber spatula for 3-4 times to combine
BAKING:
Gently pour the batter into the pan. Give the pan a few gentle shakes to even out the batter. Give the pan 3-4 firm taps on the counter. Use a skewer to run a zig zag motion to pop any large bubbles inside the batter. Tap the tube pan on the counter 3-4 times again before putting into the oven
For 7 inch cake, bake in a preheated oven for 60 minutes. For 8 inch cake, bake for 65-70 minutes on the middle rack or until a cake tester comes out clean with just a few dry crumbs. It shouldn't be wet. The top of the cake should be dry to touch and springy when you gently press on it.
Don't be alarmed if your cake has some cracks on top. What you are looking at will become the bottom of your cake
COOLING:
Once out of the oven, give the pan 3-4 taps on the counter to prevent the cake from sinking. Then carefully invert the pan upside down immediately. Your chiffon pan may have the little stands for you to inver. Please don't be tempted to remove from the pan if it's still warm. It takes about one to two hours to cool down completely
Once it's cool down completely, use an offset spatula to run through the edge of the cake to help release the cake. Use a skewer to loosen the tube area. Gently push the base of the pan up. Use an offset spatula again to run through the bottom of the cake to help release it from the base of the pan
STORING:
If you have the patience to wait, once the cake has cooled down completely and you have unmolded the cake, wrap it up in a cling wrap or store in an air-tight container and the flavor and texture gets even better the next day
The cake can be kept at room temperature for 2-3 days if it's not very humid where you are. Keep in the fridge, well-covered to prevent drying out if it's really humid
Video
Notes
Recipe adjustment for different tube size:
For 6 inch tube: use 3 eggs and multiply by 0.75 the rest of the ingredients. Bake for 50 minutes
For 9 inch tube: use the same recipe with 8-inch tube pan recipe (the one I posted on the recipe card)
For 10 inch tube: use 8 eggs and multiply by 2 the rest of the ingredients. Bake for 70-80 minutes