Make toffee sauce by combining 1¼ cups cream, butter, corn syrup, and sugar in a medium saucepan. Bring to a boil. Making sure to stir frequently, cook mixture until it becomes a deep amber color (35-40 minutes).
Whisk in remaining heavy cream and then strain the sauce through a sieve into a glass bowl. In another small saucepan, simmer dates in water on low heat for about 15 minutes (the dates should be soft). Once done, add the dates and excess liquid to a food processor and puree until smooth.
Preheat oven to 350°F. Butter 6 ramekins and set aside. Whisk flour, baking powder, baking soda, and salt in a small bowl. Set aside. In another bowl beat the butter and brown sugar together until light and fluffy. Add egg and vanilla, followed by the date puree.
Add dry ingredients and beat until smooth. Spoon batter into ramekins making sure to smooth the tops. Bake for 20 minutes or until centers come out clean when a toothpick is inserted. Let cool for 10 minutes. Trim tops of the cake to be level with the tops of the ramekins. Remove cakes and then cut in half horizontally.
Clean out ramekins and spoon 1 tablespoon of toffee sauce into the bottom of each ramekin. Layer bottoms of cakes back in the ramekins, followed by another tablespoon of toffee sauce and then the top piece of cake. Add another tablespoon of toffee sauce and spread evenly.
Place ramekins on a baking sheet and bake for 10 minutes. Let cool slightly, then remove cakes from ramekins making sure to flip the cake onto the dessert plate. Top with warmed toffee sauce and whipped cream.