Preheat oven to 350 degrees Fahrenheit.
In the bowl of an electric mixer fitted with the whisk attachment, beat whites until foamy. Slowly add in one cup of sugar and beat until stiff peaks form. Set aside.
In another bowl, beat yolks with sugar, oil, lemon juice, potato starch, and optional baking powder, scraping sides from time to time. Using a spatula, gently fold whites into yolk mixture.
In a small bowl, combine cheese with sugars and whisk until smooth. Spread evenly over cooled cake(s). Pour rest of batter over the cheese filling and return to the oven for another 50 to 55 minutes. Refrigerate overnight.
Use whipped cream to frost the chiffon cheese cake. Decorate with chocolate shavings or lemon peel.
Pour half the batter in to a 10-inch springform pan. (If you’d prefer you can make two smaller cakes using two 9-inch round pans, or you can use one 9- x 13-inch pan.) Bake for 20 to 25 minutes (depending on size of pans) until toothpick comes out clean. Remove from oven and let cool. Lower oven temperature to 325 degrees Fahrenheit.
The cake freezes well or can be refrigerated up to two days ahead.