Despite the name, this was definitely the simplest recipe we have made so far. Bublanina translates to bubble cake, so called because the cake bubbles up around the fruit. You can find the recipe we used here: https://www.thespruceeats.com/czech-bublanina-dessert-recipe-1135692
Like I said this is a simple recipe, if you can separate eggs, grate orange zest— and recognize stiff peaks you have all the skills needed for a successful outcome with this recipe. We did use an 8 x 8 pan, not the 9 x 9 recommended in the recipe for 2 reasons: 1) Eric doesn’t have a 9 x 9; 2) He made it first and let me know there wasn’t a whole lot of batter involved so an 8 x 8 would probably be better anyway. I do feel it would have been too thin in a 9 X 9.
Butter, sugar, yolks and zest 
Mix these egg whites with the butter mix add flour and…wah la…cake!
The one thing that threw me off was that this cake doesn’t brown. Same color when I took it out as when I put it in, so make sure you test the middle to make sure it’s done. Don’t put it back in til it browns.
Cake in….. 
Cake out. Dust with a little powdered sugar before you eat.
Use any fruit you want, but make sure it’s tasty. Most of the taste comes from the fruit, not the cake. It’s not as sweet as most cakes, more like a coffee cake. The blueberries were perfect, some were tart and some were sweet, paired great with the cake for a taste sensation. Eric said he put vanilla ice cream on his and it was very good but felt that his combo of raspberries/blackberries was a mistake. Too much sweet, not enough sour, so that means I take the cake (get it!) this month!
Eric’s sure does look good. 
Maybe some cherries next time?
Does look yummy. Eric’s looks yummy too.