Preheat the oven to 160 degrees C. Lightly spray a 20cm springform cake tin with cooking oil and dust with a little rice flour.
In a stainless steel bowl, beat the egg yolks and sugar with an electric mixer until thick and fluffy. Stir in the rice flour and orange juice. Fold in the almond meal and cinnamon and mix well.
In a separate stainless steel bowl, beat the egg whites with an electric mixer until fluffy and stuff. Carefully fold the eggs whites into the main mixture. Pour the mixture into the oiled and dusted springform tin and bake for 35-40 minutes. The cake is ready when a toothpick comes out clean.
To make the Orange Sauce: cream the butter and sugar. Add the cream and stir till blended. To help the cream blend you can sit the bowl over hot water (e.g. in a larger bowl or in the sink) while you stir this stage. Add orange juice and rind and blend well. Beat the egg whites until think and fluffy and fold into the sauce mixture. Serve immediately.