I just did a quick search on Eat Your Books (an amazing sight that indexes the recipes on thousands of cookbooks) and it didn't turn up a single recipe (although it did fine 31 recipes with marigold as an ingredient!). Now I want to know too.

Did you search google? I ask because when I searched "marigold cupcakes" I got several hits immediately, so I wasn't sure if you'd done that search and felt those results were not what you needed?

Basically Google searches only show that the cake looked like a pyramid with its top cut off, and that several people want the recipe. No telling results, however...sorry to be unhelpful. :)

Sweet Marigold Cupcakes

100g/4ozs softened butter
100g/4ozs castor sugar (I didn't have any and used ordinary sugar)
2 eggs
100g/4ozs self-raising flour
1 tsp baking powder
2 tablespoons fresh marigold petals

Mix all except petals in a bowl till smooth and glossy. Fold in 1 and 1/2 tablespoons marigold petals.

Spoon into cup-cake papers, sprinkle each one with remaining petals and some sugar.
Bake160C/325F about 20 mins.

I used the large size cup-cake papers inside my muffin tin. The petals on top do not brown or burn but keep their lovely orange/golden colour perfectly.

I'm sure that children would love making these little petal cakes.
Something different!

We must somehow get different google results, because I saw the recipe posted by kwash85 as well as a recipe for a chocolate based cupcake frosted with a facsimile of a marigold and made in honor of dia des los muertes.

http://www.latina.com/food/recipes/marigold-cupcakes