Upside-down banana sticky toffee pudding

In a saucepan combine the dates, milk, baking soda and seven ounces of broken-up banana; bring to a simmer, mashing, then lower to a gentle simmer and keep mashing about five minutes to a thick, coarse paste. Set aside to cool.

Trim the stems of the three remaining bananas and halve them lengthwise through the peel; lay cut side up on a quarter baking sheet, sprinkle the tablespoon of brown sugar over (about half a teaspoon each) and pat it in.

Broil, watching closely, until bubbling and charred like a crème brûlée top, about a minute and 20 seconds.

Cool until touchable, then arrange the halves in the parchment-lined, greased dish, peeling off the skins as each is placed; cut to fit.

Reduce the oven to 300 degrees after broiling.

Whisk together the flour, kosher salt and baking powder.

Cream the dark brown sugar and room-temperature butter with a hand mixer until pale and fluffy; beat in the eggs one at a time.

Add the dry ingredients in three additions alternating with the banana-date mixture in two, ending with dry; scrape the beaters, add the walnuts and fold until evenly mixed.

Pour the thick batter over the bananas, into the gaps, and smooth to the corners.

Bake at the reduced oven setting 45 to 55 minutes, until domed, browned and cracked and a tester comes out clean in several places; a banana can give a false clean test. Here it took a little over 55 minutes.

For the toffee sauce, bring the cream, dark brown sugar, kosher salt and butter to a boil over medium-high, then hold at a low boil, swirling, until the sugar dissolves and it thickens slightly; off the heat add the vanilla and keep warm on very low.

Poke holes all over the hot cake with a skewer and pour over about two thirds of a cup of the sauce; cool about 15 minutes until warm.

Invert onto a platter, remove the parchment, and brush a little more sauce over to glaze. Cut three by three; serve warm with the remaining sauce, and ice cream or whipped cream if wanted.