Witches in Space?

I had some of that ''just-add-hot-water" spiced cider today, and it got me thinking about one of my favorite books as a child. Unfortunately, I have no idea what the hell the title is.

The cider reminded me because the book was about a little witch
(well, warlock) named Witchard who lived with his aunts who were very traditional witches, and part of the story involved him going to the grocery store and buying all the ingredients to make an instant powdered version of their witches' brew. I think he and the little girl witch (who I want to say was named 'Witchina') ended up going into space at some point as well. It's been a while since I read the story.

It probably came out about the same time as the 'Little Vampire' books, because I associate the two. Anyway, if this sounds at all familiar to any of you, could you maybe let me know if you recall the title? It's really bugging me.