At least an hour before baking, pour apple brandy over the diced dates and let them soak until the dates are soft. Fire up a charcoal of chimney about 20 minutes before baking.
Prepare a 12-inch camp Dutch oven by cutting a round of parchment to fit the bottom of the oven. To create two strips of lifters, cut two pieces of parchment paper that are about 18-inches long and 4-inches wide. Fold in half lengthwise and place beneath the round of parchment paper. Spray with a light coating of oil. If you are not going to remove the cake to serve, skip adding the lifters but include the round parchment on the bottom of the oven to assist in removing and serving the slices of cake.
In a large bowl, sift together flour, sugar, baking soda, baking powder, salt, cinnamon, and ground nutmeg.
Melt butter in a small Dutch oven over two or three hot coals. Set aside to cool.
In another large bowl, toss diced apples in the juice of a freshly squeezed lemon.
Pour dry ingredients over the diced apples, then add eggs, cooled melted butter, and brandy and apples. Fold gently until all ingredients are incorporated. Do not over mix the batter.
Pour batter into prepared 12-inch camp Dutch oven.
Sprinkle crystal sugar on top of batter.
Cover oven with the lid, taking care to make sure the parchment paper lifters are square (not tucked in or at an angle) when placing the lid on the oven. Bake at 325F by placing 9 hot charcoals in a circle underneath the oven and 16 hot coals around the edge of the lid. Bake for 45 to 60 minutes or until the top is dark brown and a toothpick comes our with bits of crumb. Make sure to turn the lid clockwise and the bottom counterclockwise 1/4 turn every 15 minutes to avoid a hot spot.
Remove from heat. Let oven sit without lid in a cool, dry place until it is cool to touch. Remove cake from the oven using the parchment lifters. Dust with powder sugar.