I've tried adding jimmies to a vanilla sponge cake recipe but they sunk to the bottom of the cake. Would they not sink in another kind of cake? Any good recipe ideas?

I usually don't add them to the cake mix itself, I pour batter in the pan, sprinkle them on, pour some more and sprinkle the rest. Also try coating them with a couple of teaspoons of flour, that may help the cake mix grab on to them instead of them sinking.

I made a vanilla batter today for cupcakes and folded the jimmies in at the end, then put the batter in the tins. They did not sink. Maybe sponge cake is too light?

Both of the suggestion above are good. Another thing one can do is take about 1 cup of the dry mix and mix the jimmies in there, then add that to the rest of the mix. Coating them w/flour (or cake mix) is suppose to keep them from sinking to the bottom.

I just put the jimmies in with the dry ingredients and whisk everything together, then add the wet. Never had a problem with them sinking. I usually add 2-3 tablespoons.