Preheat oven to 175C/350F
Place the dates in a bowl and cover with boiling water and the bi-carb.
Allow to soften for 20 minutes.
Place softened dates in a blender and purée to form a date paste.
Grease a normal round 20cm/8inch cake tin.
DO NOT use a spring form tin or line with baking paper.
Pour warmed, runny caramel over bottom of cake tin, ensuring the entire surface is covered.
Place the 6 eggs whites in the bowl of a kitchen stand fitted with a whisk attachment.
Whisk on medium/high until soft peaks form then gradually add the maple syrup, 1 tablespoon at a time
Whilst still whisking on medium/high, gradually add the date purée and vanilla extract.
Add the egg yolks and whisk until combined.
Sift the dry ingredients together.
Add the dry ingredients to egg mixture and whisk on medium until combined. Gently pour cake mixture into the cake pan over the caramel, being careful not to mix the caramel into the cake.
Bake cake for 30-35 minutes, or until cake is cooked through.
Remove the cake from the oven and leave in the tin for 15 minutes.
Run a knife around the edge of the cake, and turn cake out onto serving plate.
The caramel may need to be spread out over the cake once turned.
Can be served warm or cold... and whipped coconut cream is a nice accompaniment!