For the cake, preheat to 350°F. Generously spray a 9- to 10-inch (12 cup) Bundt pan** with baking spray. Rub the spray into all the grooves of the pan with a small piece of paper toweling. Spray pan again lightly and set aside.

Whisk the flour, baking soda and salt together.

With a stand mixer fitted with a paddle attachment, or with a hand mixer in a large bowl, beat the butter until creamy. Add the sugar and beat at medium speed until pale and fluffy. Add the vanilla and the eggs (one at a time), beating for about 1 minute after each egg goes in. Reduce mixer speed to low and add in the bananas. Finally, add half the dry ingredients (the batter may curdle a bit) and mix until combined. Next add all of the buttermilk, mix again, then add the rest of the flour mixture. Scrape the sides of the bowl with a spatula and stir one more times. Transfer the batter to the prepared pan and smooth the top.

Bake for 60-75 minutes, or until a thin knife inserted deep into the center of the cake comes out clean. After 30 minutes of baking time, cover the cake loosely with foil.

When cake is finished baking, transfer it to a rack and cool for 10 minutes, invert pan and transfer cake onto the rack. Cool to room temperature. If you have time, wrap the cooled cake in plastic and allow it to sit overnight (if not don't worry, it will still be wonderful!).

Boil for ONE minute, stirring constantly. Remove from heat, stir in vanilla extract.

Add about ½ cup of the powdered sugar and whisk until smooth. Continue to whisk in powdered sugar by the tablespoon until you reach your desired consistency.

Place on a serving platter or cake stand and pour the salted toffee icing over the top. Sprinkle lightly with flaky sea salt.