Place dates and water into a medium saucepan. Bring to a boil over med heat and simmer for a couple minutes. Remove from heat and whisk in baking soda. Let sit while making the cake batter. Mash before using in cake.
Preheat oven to 350F and grease & flour three 6" cake pans.
In a medium bowl, whisk together flour and baking powder. Set aside.
Using a stand mixer fitted with a paddle attachment, cream butter and sugar on med-high (approx. 3mins). Reduce speed and add eggs one at a time fully incorporating after each addition. Add molasses and vanilla. Beat until combined.
Add flour mixture in 3 batches then add in the hot mashed dates. Beat until combined.
Divide batter evenly between prepared pans and bake until the cakes spring back when touched and a toothpick inserted into the center comes out mostly clean (approx. 40-45 mins). Make Toffee Sauce while cakes are baking.
Cool in pans on wire rack for 10mins, then turn out onto wire racks to cool completely.
Combine all ingredients in a medium saucepan and bring to a boil while whisking occasionally. Simmer for 2 minutes.
Vanilla Swiss Meringue Buttercream:
Place egg whites and sugar into the bowl of a stand mixer, whisk until combined.*
Place bowl over a double boiler on the stove and whisk constantly until the mixture is hot and no longer grainy to the touch (approx. 3mins). Or registers 160F on a candy thermometer.
Place bowl on your stand mixer and whisk on med-high until the meringue is stiff and cooled (the bowl is no longer warm to the touch (approx. 5-10mins)).
Switch to paddle attachment. Slowly add cubed butter and mix until smooth.**
Add vanilla and whip until smooth.
Trim the tops so that they are flat and so that the top crust of the cake is removed.
Poke holes into the cakes using a bamboo skewer (or something similar in size). Spoon 2-3 Tbsp of the warm toffee sauce onto each of the cake layers. Spread evenly. Cool completely.
Place one layer of cake onto a serving plate or cake stand. Top with 2/3 cup buttercream and spread evenly. Repeat with remaining layers.
Do a thin coat of frosting all over the cake. Using a large icing scraper, scrape and smooth the frosting on the sides of the cake so that some of the cake starts to show through. Smooth the top with an offset spatula.
Chill cake for 30mins.
Warm up the toffee sauce if necessary until it is pourable but not too thin and not warm.
Using a small spoon, place dollops of toffee sauce around the top edges of the cooled cake, allowing some to drip down. Fill in the top of the cake with more toffee sauce and spread evenly with an offset spatula.
* Ensure there is NO trace of egg yolks in your whites and that your mixer bowl and whisk is completely grease free or your meringue won't stiffen.** The buttercream may look like it's curdled at some point. Keep mixing until it is completely smooth.Cake recipe adapted from Rock Recipes.