I want to make a banana cake with a sautéed banana filling. Would the bananas still blacken? I don't want to cut into the cake only to find unappetizing bananas inside!
Are you doing something "banana's foster-y" or do you just want to caramelize bananas on the outside? I've made a brown sugar, brown butter, banana, cinnamon compote and cooled it to fill a cake. It didn't blacken, but it was definitely an earthy brown color. I didn't find it unappetizing, but if you're looking for banana yellow, you'd be disappointed.
Simply sautéed bananas, though, I'm afraid would probably oxidize. Even when I make banana cream pie, the bananas inside oxidize a little. If I'm working with bananas, I'm making sure always that I'm making the dessert as close to serving as possible.
Cooked bananas tend to be more brownish than black. I recently made banana jam and it looks like caramel: golden brown. I don't have a problem with this. But if you want something more appealing in appearance, maybe you could mix the sauteed bananas into a buttercream frosting, some sort of pastry cream or make a curd with banana. Pictures of banana cake filling that I've seen online aren't black or brown at all.
I'm fine with a caramel-brown (I.e) like a bananas foster. What I don't want it that's kind of Greyish color that comes with spiced raw bananas. I would be cooking the banana in a brown sugar syrup.
Also, both the jam and the compote sound amazing. Any tried and true recipes you'd like to pass along?
Here's the jam recipe:
you can use turbinado sugar on top of fresh banana and use a culinary torch to just caramelize the top of the bananas, they look really pretty that way. My favorite filling with banana cake is marscapone frosting.