Mix the sugar and eggs together until mixed and fluffy. Add the almond flour and baking powder in the mix.
Fold the zest and the juice of the orange through the mixed and put into a well butter tin. If you want to keep this glutenfree dust the tin after buttering with icing sugar, if not you can dust with flour instead. (this will make sure the cake can be taken out of the tin easier)
Put into the oven and bake for about 45 minutes or until the top is golden and crisp.
Leave to cool completely in the tin before removing.