Heat oven to 350°. Prepare an 8x8-inch baking dish and spray with cooking spray. Set aside.
In a small bowl, combine the flour, baking powder, cinnamon, ginger, nutmeg, baking soda, and salt. Stir with a wire whisk to break up any clumps.
In a larger mixing bowl, combine the melted butter, brown sugar, egg, milk, and vanilla extract. Stir with the wire whisk until combined.
Add the dry ingredients into the wet ingredients and stir together with a wooden spoon or spatula. Add the chopped apples and mix together.
Evenly spread the cake batter into the prepared baking dish.
MAKE THE APPLE CIDER SYRUP : In a saucepan, over medium high heat, combine the apple cider, brown sugar, vanilla extract, and cinnamon. Stir with a whisk to combine. Bring to a boil. Once boiling, take it off the heat and gently pour it over the cake batter in the baking dish. DO NOT stir it into the cake. Just pour it over top and let it be.
Bake for 25-30 minutes. * Cake should look puffy on the edges but it does not have to be entirely cooked as it will cook 10 more minutes after the streusel.
While the cake is baking make the BROWN SUGAR STREUSEL : Combine all ingredients into a small bowl and use your hands/fingers, a fork, or a pastry cutter to mix it together until coarse, moist crumbs form.
After the bake time take the cake out of the oven and sprinkle the streusel over top. Put it back in the oven to bake for 10 more minutes. * A toothpick inserted into the top portion of the cake should come out clean. Beneath the cake will be the apple cider caramel so it will come out wet if you stick the toothpick all the way to the bottom of the pan. Just test the top cake portion for doneness.
Serve the cake warm with a scoop of vanilla ice cream and caramel drizzle if wanted.