Preheat the oven to 190°C. Spray a 9in cake pan with low calorie cooking spray and line the base with baking parchment.
In a one bowl, whisk the eggs, almond extract and 60g of sweetener until the mixture is thick and leaves a trail. This will take quite a while but be patient.
In another bowl, mix together the flour, baking powder, and ground almonds and fold into the egg mixture with a metal spoon. Stir in half of the orange zest.
Spoon this mixture into the prepared cake pan, place in the oven and bake for 25–30 minutes or until the cake has risen and is just firm to the touch (Insert a skewer and if it comes out clean the cake is ready).
While you're waiting for the cake to cook, heat up the orange juice, remaining orange zest and remaining 15g of sweetener until it dissolves.
When the cake is cooked pour half of the syrup mixture over the top and leave the cake in the pan for 10 minutes.
Remove from the cake pan and allow to cool completely on a cooling rack.
When cool, cut into 12 portions, and serve with a little of the remaining syrup drizzled over the top.