Top of the bill has to be Astro Cake (renamed Comet Cake), which was made by Oopsy with (no) help from Pootle - a three-layer sponge sandwiched with jam and topped with icing, chocolate moons, jelly stars, sprinkles, and a shooting star on a stick. Another cakey option is the chocolate cake Stella makes for Ray on bath days, but frankly Astro Cake has the wow factor here. It should be easy enough to recreate if you can only find the right toppings! I think I am definitely up for this one.
Making regular appearances are Oopsy's Crackle Cakes. I like to think of these as chocolate crispie cakes, maybe with a dash of popping candy for real crackle, topped with white chocolate and a cherry. Small Person and I have actually just made something very similar for Daddy's birthday...
Sunwiches have to be a party staple, especially as they are so flexible. Jam (as found by the treasure map) and cheese have both cropped up, in fact I think Oopsy names several cheeses in her skipping rhyme. Perhaps Bud-D's boiled eggs could provide another filling (presumably with moon mayo). But really you could have almost anything with a suitably space-y name.
You can't forget Groobie's favourite, sausages. Maybe not with gravy, peas, parsnips, cheese, or onion rings, but sticky mini sausages on good old fashioned cocktail sticks would surely be a winner. Another option could be Mouldy Meteors - mini meatballs made with the addition of some sort of green veg for the 'mould' (edging towards Halloween there...), or for a meat-free option maybe mini felafel with herbs in.
Wobblyfruit would be awesome too - orange jelly would do the trick. And what else would you serve it with but Cosmic Whipple Ripple ice cream? Swirling together a couple of different ice cream colours/flavours with fruit sauce or sweeties would be one way to do it.
It's not all sweets and treats, there's healthy options too. Fruit and veg make various appearances, from Ray's favourite Tangle Berries (when not being used for Groobie's special... eyebrow shampoo... *cough*) to Stella's Moon Marrows, Evenfruit, and the suspiciously rhubarb-like Lunar Sticks that nearly left Oopsy stranded on Bockety Moon. I reckon you could at least have a platter of veg sticks from Stella's patch on your party table, but you'd have to come up with good names for them all :)
And of course, we need something to drink. What else but a selection of smoothies? Combinations of fruits and yogurt, maybe some sparkling water for proper astro-fizziness, and you're all set. Oh for a magic smoothie machine like Groobie's that can dispense whatever you wish for!
I'll be keeping an eye out for other ideas as the day approaches, but to be honest I think a full-on Pootle Party would suit an older child better. So let's just hope the Okidoki addiction lasts a while longer :)