I’ve never made a layer cake with frosting in my life, but I do like baking fruit cakes. Not the kind you make for Christmas (though I suspect they get an undeservedly bad rap), but simple cakes that involve fruit covered in batter. They’re easy to make, reasonably light, work for breakfast or dessert, go well with coffee, tea, milk, etc.
Sour apples like Granny Smith work really well in these cakes, but so do rhubarb, strawberries, peaches, blueberries--anything that's tart. You don't need to do anything with the fruit besides cut it into chunks, and frozen berries work great. It doesn’t hurt to add a bit of vanilla or cinnamon to the batter. See the recipes below for details.
These are the variations I like:
The classic Russian charlotte: 3 eggs, 1 cup sugar, 1 cup flour, ½ tsp. baking powder; mix; pour over fruit chunks; bake 60 minutes at 370. Here's my old apple charlotte recipe.
Yogurt cake: Similar to the above, but with 1/2 cup of plain yogurt and sour cream, and a bit of oil for extra richness.A few weeks ago I made this cake using peaches for the fruit; recipe here.
Buttery cakes with a bit of yogurt or kefr for richness and moisture. See this rhubarb cake recipe for details.