This trick works best with plain, soft, white bread, as it won't affect flavor of the cake. If your bread slices don't seem to stand upright, use a few toothpicks to gently secure them to the cake.

2 cups all-purpose flour; 1 cup granulated sugar; 1/2 cup unsalted butter, softened; 1 cup milk; 2 large eggs; 1 tbsp baking powder; 1/2 tsp salt; 2 cups onions, finely chopped (about 2 medium onions) ...