How to Make It
Preheat the oven to 350°. Coat a 10-inch round cake pan with nonstick spray and line with parchment paper. In a saucepan, cover the dates with 1 cup of water; bring to a boil. Remove the pan from the heat and whisk in the baking soda; it will foam up. Let cool slightly.
In a medium bowl, sift the flour with the baking powder and salt. In a stand mixer fitted with the paddle, beat the butter with the granulated sugar at medium speed until light and fluffy, 1 to 2 minutes. Beat in the eggs and vanilla. In 2 alternating batches, beat in the dry ingredients and the date mixture until just incorporated. Scrape the batter into the prepared pan and bake for 35 to 40 minutes, until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10 minutes.
In a medium saucepan, bring the brown sugar, butter and heavy cream to a boil over moderate heat, whisking to dissolve the sugar. Simmer over moderately low heat, whisking, for 2 minutes. Remove from the heat; whisk in the brandy, vanilla and salt. Keep warm.
Turn the cake out onto a rack and peel off the parchment. Carefully return the cake, top side down, to the pan. Using a skewer, poke 15 to 20 holes in it. Pour half of the warm sauce over the cake and let stand until absorbed, about 5 minutes. Invert onto a platter and poke another 15 to 20 holes in the top. Pour the remaining sauce over the top. Serve warm.
Vanilla ice cream or crème fraîche.