Preheat Oven & Prep Pan: Set your oven to 180ºC (350ºF). Prepare a 9-inch x 5-inch rectangle baking pan by lining it with parchment paper. For non-stick pans, grease with soft butter, line only the base with parchment, and dust the sides with a light layer of flour for smooth cake edges. Set aside.
Steep Tea: Pour boiling water into a large heatproof jug, add tea bags, and steep for 10 minutes.
Prepare Dates: While the tea steeps, pulse dates in a high-speed food processor until they are chopped into small chunks. Alternatively, chop the dates manually with a sharp knife.
Soak Dates: Transfer the chopped dates to a large mixing bowl. Once the tea is ready, discard the tea bags and pour water over the dates, ensuring they are well covered, and allow to soak for 10 minutes.
Combine Wet Ingredients: To the soaked dates, (keep the liquid, do not discard) add the sugar and whisk until well combined. Then, whisk through the egg until fully incorporated.
Mix Dry Ingredients: Sift flour, baking powder, baking soda, and allspice directly into the wet mixture. Use a silicone spatula to gently fold the ingredients until just combined, ensuring there are no large pockets of flour.
Transfer Batter: Pour the batter into the prepared baking pan, smoothing out the top.
Bake: Bake for 40-43 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
Cool: Remove from the oven and let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Serve: Enjoy the cake warm or cold, ideally with a spread of butter or your favorite accompaniment.