Preheat the oven to 200?C/gas mark 6.Melt the butter and set aside. Line a 12 hole muffinn tray with 12 paper cases.
Combine the flour, ground almonds, bicarb, baking powder, sugar and orange zest in a large bowl. Measure the orange juice and milk into a jug and whisk in the egg and then the cooled, melted butter.
Now pour the liquid ingredients into the dry ingredients, mixing with a fork as you go. The batter will be lumpy but that’s as it should be: you want everything to be no more than barely combined. The whole point of muffin mixture is that it must never be overworked.
Spoon out the mixture equally into the muffin cases and cook for 20 minutes. Remove, in their paper cases, to a wire rack and let cool slightly (but not completely) before devouring.