Preheat the oven to 375 degrees F. Coat a 9 by 9 by 2-inch pan with nonstick oil-and-flour baking spray, then set aside.
Whisk the cake and spice mixes, the ginger and baking soda together in a large bowl to combine. Add the berries and toss well. Make a well in the middle of the dry ingredients.
Whisk the buttermilk, molasses, and eggs in a 1-quart measure until smooth. Pour into the well in the dry ingredients, then fold in using a large rubber spatula. The batter should be lumpy with a few floury specks still clearly visible.
Scoop the batter into the pan, spreading to the corners, and sprinkle the spiced sugar evenly on top. Bake in the lower third of the oven until lightly brown and a cake taster inserted into the middle of the gingerbread comes out clean, 25 to 30 minutes.
Cool the gingerbread in the upright pan on a wire rack to room temperature, cut into large squares, and serve.
Churn the flour, sugar, baking powder, and salt in a food processor fitted with the metal chopping blade a couple of seconds until well blended. Tap 1/2 the mixture onto a large piece of waxed paper and reserve.
Scatter 1/2 the butter evenly over the dry ingredients in the processor and pulse 6 to 8 times. Scrape the work bowl and stir, pushing larger pieces of butter to the bottom. Pulse quickly 3 to 5 times more until the mixture is about the texture of lentils. Empty the mixture into a large mixing bowl.
Return the reserved dry mixture to the food processor, scatter the remaining butter evenly on top, and cut in as before. Add to the mixture in the bowl.
Toss the 2 batches together well, then spoon into a large zipper freezer bag, press out all the air, and seal. Label, date, and store in the refrigerator or freezer. This quick cake mix will last at least two months in the freezer, 1 week to 10 days in the refrigerator.
Scoop out the cold or frozen mix - no need to thaw - and use as individual recipes direct.
Place the 3 spices in a small bowl and whisk until well blended.
Spoon 1/2 of the spice mix into an 8-ounce preserving jar, rap against the counter until the mixture compacts a bit. Add the remaining spice mixture and compact as before.
Screw the lid down tight, label, and date the jar of spice mix, then store on a cool, dry, dark shelf. Use as recipes direct.
Recipe courtesy Jean Anderson, Quick Loaves, HarperCollins, 2005