Preheat the oven to 180 “C. Place rhubarb, caster sugar and water in a roasting pan.
Arrange the rhubarb in a single layer, cover with aluminium foil and bake for 15 minutes or until rhubarb is soft but holding its shape.
let it cool down, drain rhubarb and reserve the syrup.
In a large bowl, combine the sour cream, oil, sugar, and eggs, stirring until well blended.
Add the all-purpose flour, almond flour, baking powder, salt and extracts. Stir to combine. Add the sour cream and stir well.
Grease 8 inch baking pan. Pour the batter into a prepared pan. Arrange the baked rhubarb on the top and sprinkle slivered almonds on the side.
Bake for 35-45 minutes, until the cake feels springy to the touch in the centre and a toothpick or cake tester inserted into the centre comes out clean.