Sweet Potato Chiffon Cake

I wanted to make chiffon cake.  I tried to make Kabocha Chiffon Cake the other night, and it flopped!!  the weight of the Kabocha and liquid were too much for the meringue to handle. It's a night mare when you can't even read your own recipe notes on the paper you jotted. So back to the drawing board to troubleshoot what I did wrong.  This time, back to normal - it worked. 
Ingredients:
7 Organic Large eggs - washed and at room temperature - separated as follows
       7 Egg Whites - egg white in mixer bowl with whisk attachment
       7 Egg Yolks in a medium bowl
150 g Organic Cane Sugar
60 g Organic Cane Sugar
Cooked Organic sweet potatoes - 9 oz - strained through sieve
160 g Organic Non-GMO Home mixed Pastry Flour
90 ml Organic milk
60 ml Organic Avocado Oil
1/4 tsp Kosher Salt
Preheat oven to 235'F
Depending on your oven's BTU, Bake 50 min to 1 hr 7 min.

Method:  Add 60 g sugar, 90 mil milk, 60 ml Avocado Oil, 9 oz strained sweet potato to the bowl with egg yolks.  Shift 160 g flour.  Add flour to the egg mixture.  Gently mix them all.  Set aside covered.
Make meringue - Beat egg whites with 150 g sugar until stiff peak forms.
Add 2 C of meringue to egg yolk mixture.
To make sure egg whites are mixed in thoroughly, stir the meringue with spatula in gentle whirl pool at the top and pick up the batter at each pass through.  Repeat this method until all meringue are mixed in. Then, fold from bottom and over with spatula.