Preheat the oven to 350°F. Grease a 9x9 inch light metal baking pan and line it with parchment paper.
In a medium bowl, whisk together the flour, cinnamon, nutmeg, allspice, baking soda, and salt. Then set aside the flour mixture.
1 3/4 cups (219 g) all purpose flour, spooned and leveled, 1 tbsp cinnamon, 1 tsp nutmeg, 1/4 tsp allspice, 1 tsp baking soda, 1/2 tsp salt
Add the softened butter and granulated white sugar to a large bowl. Cream together for 2 minutes with an electric mixer on high speed.
1/2 cup (112 g) unsalted butter, softened, 1 cup (200 g) granulated white sugar
Then add in the eggs and vanilla and mix on medium speed until pale in color and smooth, about 1 minute.
2 eggs, at room temperature, 1 tsp vanilla
Add in the unsweetened apple butter and buttermilk and mix on medium low speed until combined. (The batter will look curdled at this point but don't worry. It will pull together once the dry ingredients are added.) 1 cup (244 g) unsweetened apple butter, 3/4 cup (180 ml) buttermilk, at room temperature
Add the dry ingredients to the wet ingredients and mix on medium low speed just until the batter is combined. Scrape the sides of the bowl with a rubber spatula as necessary
Pour the batter into the prepared pan. Sprinkle the apples on top of the batter, then sprinkle the chilled streusel on top of the apples, making sure to cover the entire top in an even layer.
Bake the coffee cake for 65-80 minutes, or until a toothpick comes out clean from the center with only a few moist crumbs.(If the top is getting too brown towards the end of the baking time, loosely cover with aluminum foil.) Let the cake cool in the pan on a wire rack for 30 minutes, then pull up on the parchment paper to release it from the pan. Let the crumb cake continue cooling on the cooling rack until completely cooled.