I made a burger cake for my brother's birthday. I made the cake and fondant in the morning and assembled everything in the evening a day ahead. Basically yellow cake mix, devil's food cake mix, home made marshmallow fondant, 1 green fruit roll up, cream cheese frosting and lots of food coloring. I hope you like! Also posted on my blog. Feel free to comment!

Looks really nice in real life.

sparkling candles!

most of the fondant "fixings" were kept to the rim of the cake, we didn't want all the extra sugar!

doesn't that cheese look so real??
Tutorial:Supplies:Yellow cake mix
Devil’s food cake mix (or any chocolate cake mix)
Eggs, oil and water for the cake mixes
9″ round pans
Large oven-safe glass bowl
Fondant (1/2 recipe of marshmallow fondant -
http://whatscookingamerica.net/PegW/Fondant.htm)
Frosting of choice (I used a tub of cream cheese frosting)
Vegetable shortening for greasing pans and working with fondant
Food coloring (red, yellow, green)
Green fruit roll up (optional - for pickles)
Large plate to put cake on
Parchment/wax/regular paper for cake assembly(optional)
Instructions:1. Buns: mix up yellow cake mix according to directions. Grease up cake pan and bowl with shortening. You can also use parchment paper to line bottom of the cake pan. Pour half or a little less than half of the cake batter into the 9" round pan and the rest into the oven-safe glass bowl. Bake according to directions on box and use a tooth pick to check for doneness. (If toothpick comes out clean, it's done.) Let cakes cool for 10-15 minutes then carefully remove from pan to finish cooling. If not using immediately, wrap cooled cakes in plastic wrap to keep from drying out.
The bowl I used was a Pyrex 7.5Q one. Since I had a clear bowl, I just put my cake pan into the bowl and looked through the side of the bowl to see if the bowl would make a good top bun. Mark where the bottom of the cake pan touches the bowl and that's approximately where you would pour your batter to.

2. Meat: mix up devil's food cake mix according to directions and bake in two greased 9" round pans. Again, cool for 10-15 minutes and remove from pans. Wrap cooled cakes in plastic wrap if not using immediately to keep it moist. We're only using half of the cake. Use the other half for cupcake pops or something!
3. Make the fondant. Portion off some for lettuce, tomatoes, onions, cheese and pickles (if not using fruit roll up for pickles. Tint fondant with food coloring. I recommend gloves and working on a baking sheet or something to prevent coloring your table. If fondant is too sticky, add some more powdered sugar or grease your hands well with shortening.
4. Place four pieces of parchment/wax paper along the perimeter of the cake plate leaving the center empty. Place your bottom "bun" on center of the plate on top of the paper so that the tray is not visible around the cake edge. This is to keep the plate clean as you assemble and the paper will be pulled out from under the cake when you're finished. Put a layer of white frosting "mayo" on the bun. (Order of assembly up to you! This is how I did it.)
5. Make the fondant "cheese" as shown.

Place onto cake with corners hanging off.
6. Place the burger "meat" on top of the cheese.
7. Tint some frosting red for "ketchup and spread onto "meat". Roll out some green fondant and cut strips out. I used the edges of my rolled out piece of fondant for the curvy random edge and re-rolled the ball of fondant for more curvy edges. Wrinkle the strips so it looks like lettuce. Place along the edge with some hanging out.
8. Make red fondant "tomatoes", white fondant "onion rings", and green fruit roll up "pickles". The fruit roll up was squished into a few balls and microwaved to make it soft. It's pretty annoying to work with.. fondant would have been easier. Place along edge of cake.

9. Make sesame seeds out of white fondant and glue onto top bun with white frosting.
10. Place top bun onto cake, fill in empty gaps with more "mayo" or "ketchup" frosting. Carefully remove pieces of paper from cake plate by pulling outwards slowly.
Whew that was long, I hope this helped! Feel free to ask if anything is confusing.