Passover orange and apricot sponge cake with citrus mascarpone frosting

I know that I just posted a sponge cake recipe. But come on, that was over a week ago, and this one is different. And it's Passover. This one is good. Different, but good. Ok, it's not too different, but a little. Still, it's just as good, and has this oh so dreamy frosting. I made up the frosting. I had some stuff, I mixed it together, and ooooooooh, baby. It's like if cream cheese frosting (heavy) and whipped cream (light and airy) had a baby, and it fell in a puddle of sunshine. That might be the best food description I've come up with yet. Anyway, try it. Or don't, but you're missing out. Happy Passover, guys. I'll be posting more Passover recipes over the next few days. Better late than never, eh? And I know I should have made a frosting without dairy, but I'm not Kosher. You can leave it out, or make a lemon glaze (simple syrup with a bit of lemon juice) or use something else, but this is so dreamy. 
Orange and apricot sponge cake for Passover, or you know, a weekday. 

Based on a recipe from the Gourmet Jewish Cook by Judy Zeidler, a very interesting cookbook I got from Alex a while ago. Cheap on Amazon!

8 eggs, separated

pinch of salt

1 1/2 c sugar

3 T teff (optional, use something else if you don't have teff, the recipe originally called for almond meal, but I'm out)

1/2 c tapioca starch 

3/4 c rice flour mix (you can use potato starch if you aren't eating any grains, I'm out of that too)

3 T orange juice

3 T apricot jam (or your choice)

Preheat oven to 350. Beat the egg whites with a pinch of salt until they hold soft peaks. Add 3/4 c of sugar and continue beating until stiff but not dry. Set aside. Beat together the rest of the ingredients until well combined, then fold in part of the egg whites to lighten. Fold in the rest of the egg whites, and spread the batter evenly in an ungreased tube pan and bake 45-55 minutes. Cool upside down, then spread with citrus mascarpone frosting. 

Citrus mascarpone frosting

From my brain

1/2 c heavy cream

1/3 c sugar

1 T orange juice

juice and zest from 1 lemon

2 T apricot jam

8oz mascarpone, room temperature

Whip the cream and sugar until fluffy (don't overwhip!). Add in the orange juice and lemon juice and zest, then the jam. Fold in the mascarpone, and mix until combined. Keep chilled.