This is how he says he made it:
"I just mixed half a bag of Doves Farm Gluten Free white bread flour (about 500g) with some melted butter and some liquid consisting of about 60% homemade kefir and the rest was filtered water and an assortment of vinegars and a little sugar, to make a rather stiff dough.
Then I left it for 2 days on the side in a glass jar.
Last night I added 2 eggs and gave it a good stir, and poured it into the silicone mould. This morning I baked it for an hour at about 160 degrees C."
It tasted delicious and was really light. Well done Daniel.