Preheat the oven to 350°F.
Prepare two round or oval cake pans. (The small oval cake pans in the photo are made by Wilton and available to go with their Level 2 or Level 3 cake decorating class materials.) Either grease and flour the pans liberally, or cut a piece of wax paper to fit the bottom of the pan, grease the bottom of the pan lightly, stick the paper to the pan, and then grease the paper.
Stir the flour and the baking powder together in a small bowl.
In the large bowl of an electric mixer, cream the butter and add the sugar, unbeaten eggs, flour/baking powder mixture, and the lemon peel. Mix together slowly for one minute, and then beat on medium speed for two minutes. The mixture should turn a light yellow.
Place 1/2 cup of the cake mixture into each pan, and smooth it down until it forms an even layer. Bake for 12 to 15 minutes, until done.
After you remove the cake layers from the oven, let them rest a minute and then loosen them with a metal spatula or something similar (don't use a rubber spatula that will melt from the heat). Turn each layer carefully onto a cooling surface like a cake cooling rack. Let them cool for 20 minutes or so.
Repeat the baking and cooling until you are out of batter. You should get 6 - 8 layers. I got seven, with the last layer a bit thicker than the others. I used it as the bottom layer to provide stability.
Once your layers are cool, assemble them. Between each layer, spread a thin layer of marmalade. If you have two types of marmalade, alternate flavors with each layer. Top your cake with a healthy sprinkle of powdered sugar. Refrigerate until needed, and then let it come back to room temperature before cutting.