Step 1: Simmer 2 cups of apple cider in a saucepan over medium heat until reduced to 1/2 cup. Set aside to cool.
Step 2: Place chopped dates in a bowl with 1 cup of boiling water and 1 tsp baking soda. Let sit for 10 minutes, then mash into a paste.
Step 3: Preheat your oven to 350°F (175°C) and grease a 9x9 inch baking pan.
Step 4: Cream the softened butter and dark brown sugar together until light. Add eggs one at a time, followed by vanilla and 1/4 cup of the cider reduction.
Step 5: Whisk together flour, baking powder, salt, cinnamon, and ginger. Fold the dry ingredients and the date paste into the wet mixture until just combined.
Step 6: Pour batter into the prepared pan and bake for 35-40 minutes, or until a skewer comes out clean.
Step 7: While the cake bakes, make the sauce: combine heavy cream, 1/2 cup butter, 1 cup brown sugar, and the remaining 1/4 cup cider reduction in a saucepan. Bring to a boil for 3 minutes.
Step 8: Poke holes in the warm cake and pour half the sauce over it. Serve the remaining sauce on individual portions.