Note: Have all ingredients at room temperature before starting.
Heat the oven to 350°F and arrange a rack in the middle. Coat 8 (6-ounce) ramekins with butter and flour, set aside.

Combine dates, water, and baking soda in a small saucepan over high heat. Bring to a boil, then remove from heat, set aside.

Combine salt and flour in a medium bowl, whisk to combine, set aside. Bring a medium pot of water to a boil over high heat for a water bath. Combine butter and brown sugar in the bowl of a stand mixer fitted with a paddle attachment and beat on medium speed until light and airy, about 5 minutes, stopping occasionally to scrape down the sides of the bowl. Add vanilla extract, then beat in eggs one at a time, just until incorporated. Remove the bowl from the mixer and stir in date mixture until well combined, then stir in flour mixture until just incorporated (don’t overmix).
Divide batter evenly among prepared ramekins and set them in a roasting pan or baking dish (you will likely need to use both a 13 x 9-inch dish and an 8 x 8-inch dish to fit them all).
Pour simmering water into the bottom of the baking dishes until it reaches halfway up the sides of the ramekins.
Very carefully place the baking dishes on the center rack of the oven.
Bake until the center of each cake is just set and a cake tester inserted into the middle of each comes out clean, about 50 to 60 minutes.
Meanwhile, prepare the toffee sauce.

Toffee Sauce
Melt butter in a medium saucepan over medium heat. When it foams, add brown sugar and vanilla, stir once, and heat until bubbling and the color of maple syrup, about 5 minutes. Carefully add cream in a slow stream while stirring, and cook until it bubbles up and increases in volume, about 2 minutes; remove from heat.

When cakes are finished, remove the ramekins from the oven and place on a cooling rack to come to room temperature.
Once cakes are cool, run a knife around the perimeter of each and invert to remove from the ramekins, then place upright on a serving plate.
Serve cakes at room temperature or slightly warmed, covered in warm toffee sauce.