Step 1: In a small saucepan, bring the apple cider to a boil and cook until reduced to 1/2 cup (about 10-12 minutes).
Step 2: Add the chopped dates to the hot cider reduction, stir in the baking soda, and let sit for 10 minutes to soften.
Step 3: Preheat your oven to 350°F (175°C) and grease an 8×8 inch baking dish.
Step 4: In a medium bowl, whisk together the flour, baking powder, salt, cinnamon, and ginger.
Step 5: In a large bowl, cream the softened butter and brown sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
Step 6: Gradually fold the dry ingredients into the butter mixture, then stir in the date and cider mixture (including the liquid).
Step 7: Pour the batter into the prepared dish and bake for 30-35 minutes, or until a toothpick comes out clean.
Step 8: While the cake bakes, make the sauce by simmering butter, heavy cream, brown sugar, and salt in a saucepan for 5 minutes until thickened.
Step 9: Poke holes in the warm cake and pour half the sauce over it. Serve individual portions with the remaining warm sauce.