Make sure you dates are chopped and the pit from the middle is removed.
Add chopped dates to a medium size bowl, pour over boiling water, stir in baking soda, and let sit 10 minutes to soften. Mash lightly with a fork (a few small chunks are okay).
1 cup 6 oz / 170 g Medjool dates, ¾ cup 180 ml boiling water, ½ teaspoon baking soda
Preheat oven to 350°F (175°C). Grease and line an 8x8-inch baking pan with parchment paper. Set aside.
In a medium bowl, whisk together flour, baking powder, salt, and HALF OF THE CHAI SPICE MIX!
1 cup 120 g all-purpose flour, 1 teaspoon baking powder, ¼ teaspoon salt
In a large bowl, whisk together brown sugar, melted butter, eggs, pumpkin purée, and vanilla until smooth and slightly thickened.
½ cup 100 g packed dark brown sugar, ¼ cup 55 g unsalted butter, 2 large eggs room temperature, ½ cup 120 g pumpkin purée, 1 teaspoon vanilla extract
Stir in the softened date mixture.
Fold in dry ingredients until just combined. Spread batter evenly into the prepared pan.
Bake 25–30 minutes, or until the cake is golden, set in the center, and a toothpick comes out with a few moist crumbs.
For the toffee sauce
In a saucepan over medium heat, melt butter with brown sugar, heavy cream, and the other half of chai spice mix. Bring to a gentle boil, stirring constantly, until smooth and slightly thickened, 3–5 minutes (the sauce should coat the back of a spoon).
½ cup 115 g unsalted butter, 1 cup 200 g packed brown sugar, 1 cup 240 ml heavy cream
Remove from heat and stir in vanilla and salt. The sauce will continue to thicken slightly as it cools.
1 teaspoon pure vanilla extract, Pinch of salt
To serve
Poke the warm cake all over with a skewer or fork so the sauce can soak in. Pour half of the toffee sauce on top.
Cut into squares and serve warm with the remaining sauce spooned over each piece, plus whipped cream or vanilla ice cream.