Preheat the oven to 350°F. Butter (or spray with oil) a 9” square baking dish line it with a a piece of parchment paper long enough to hang over the sides to create a sling.
In a large saute pan, boil the apple cider until reduced by half, about 5 minutes. Measure to ensure it is ¾ cup. Add the butter to the hot cider, and whisk to combine.
In a medium bowl, whisk together the eggs, granulated sugar, brown sugar, oil, sour cream, baking powder, baking soda, cinnamon, allspice and salt.
Slowly whisk the boiled cider into the wet mixture.
Stir in the flour to combine.
Pour the batter into the prepared baking dish.
Bake in the pre-heated oven until the cake is puffed, golden and baked through the middle, about 22-25 minutes.
Place the cake on a cooling rack for 5 minutes.
Place the butter on top of the cake, and brush it around as it melts
In a small bowl, mix together ¼ cup of granulated sugar and 1 teaspoon of ground cinnamon. Sprinkle the cinnamon sugar mixture liberally over the buttered surface.
Remove the cake from the pan, and let it cool on the rack.
Allow the cake to cool slightly before cutting it into squares.
