- In a blender, purée the dates with 180 ml (3/4 cup) of water until smooth. Set aside.
- In a saucepan, bring 60 ml (1/4 cup) of water, the sugar and corn syrup to a boil. Clean the sides of the pan with a wet brush to remove any sugar crystals. Cook without stirring until the mixture turns golden brown. Off the heat, gradually add the puréed dates. Beware of splashes. Bring to a boil, stirring until the mixture is smooth. Let cool and refrigerate until the mixture is room temperature.
- With the rack in the middle position, preheat the oven to 180 °C (350 °F). Butter a 20-cm (8-inch) springform pan. Line the bottom with parchment paper.
- In a bowl, combine the flour, baking powder, baking soda and salt. Set aside.
- In another bowl, cream the butter with the brown sugar and dates with an electric mixer. Add the eggs, one at a time, and whisk until smooth.
- On low speed, add the dry ingredients alternately with the sour cream and milk. Spoon the batter into the prepared pan. Carefully pour the caramel over the entire surface of the cake. Bake for about 1 hour or until a toothpick inserted in the centre of the cake comes out clean.
- Let cool. Unmould and cool completely on a rack without removing from the pan’s bottom.