I remember making these when I was a kid… What a fun and unusual treat for Easter and/or Spring in general.  I could totally see these for a baby shower brunch at each place setting, maybe topped with an edible flower.  The how-to is below!

How to make Cake Eggs:

All you need:
Egg shells (Jumbo would yield larger results, but in this case, I thought brown would be pretty.)
Your favorite light in texture cake batter (for these I just used a white cake mix)

Using an icepick or other sharp pointy object, make a hole in the top of each egg shell. Carefully! Then enlarge the hole to about a 1/2 inch in diameter by carefully removing little bits of shell.
Pour out the insides and reserve for your cake batter, and/or other uses. (If you need to separate eggs for your cake batter, like I did, just pour out the whites first into one bowl, then use a toothpick to break up the yolk, and pour it into a separate bowl. Otherwise, just use a toothpick to mix the egg up a bit in the shell, then pour out.

Wash your egg shells.
Looking for more info, I googled and found these instructions, which suggest the egg shells should then be soaked in salty water for 30 minutes. I have no idea if this is necessary, but I decided to try that. That recipe also suggested drizzling a little oil in the shells, but I found that problematic. Since I’m serving these in their shells, I’d just skip that, or try a squirt of non stick spray.

After your eggshells are dry, it’s time to fill and bake them!
A mini muffin tin was the perfect size to hold the eggs upright for filling and baking. If your eggs don’t fit perfectly, you might add salt or sand to the cups to provide stability, or place a little foil in the cups to fill in the space.

Put your cake batter in a piping bag or a plastic baggie with a corner cut off, and pipe batter into egg shells, filling about 2/3 of the way up.

If you’ve overfilled your eggs, you will have batter that comes out the top. So put a sheet pan under your muffin tin to catch any extra that might drip off.

Bake according to the cake directions (temperature) for about 20 minutes (use cupcake directions as a guide, though these will be smaller so may not take as long.) Use the toothpick test to determine doneness.

If your eggs have overflowed, just knock off the excess. Let cool. If you place your eggs in an air tight container or zip bag, any cake on the outside of the eggs will easily wipe off after resting.

Egg cups make the perfect serving dish. Or, serve a set in a clean egg carton! If you want to add a dollop of icing or whipped cream, peel a little of the shell off the top, and decorate as desired. You could also just top the egg with an edible flower, and let the cake be a bit of a surprise!

You could also fancy these up by painting the shells with a little food coloring or similar, after baking!

(thanks to Grieg for helping me with the photos!)