Best type of cake batter for moulds?

[MinnieBar]

I bought some silicone Easter moulds this week and I don't know what type of cake would be best to get the most clear pattern, can anyone advise please?

Would a 'heavier' buttermilk-type be best, or just a normal fairy cake mix?

Or will it make absolutely no difference and come out rubbish anyway?!

Bump for evening crowd!

Last night I tried a fairly runny cake mix in mine, thinking if it was runny then it would fill the details better.
But it all stuck when I turned it out.
Did you have any success?

Some - buttermilk worked well, but only when I had the patience to wait for them to cool before I turned them out!

Plus if I put the mixture right up to the top they overflowed, but if I put it only halfway then they rose unevenly and not all the way to the top.

Must keep trying?