Heat oven to 350°F. Prepare two 8-inch round cake pans with pan release or butter & flour.
Add prunes and dried cherries to medium saucepan. Pour in 1 cup of Dr. Pepper, then bring it to a slow boil over medium heat.
Cook for 5 minutes. Then, remove it from the heat and set it aside to cool for about 20 minutes.
Boil ½ cup water. In a microwave-safe dish, melt butter. Add cocoa to melted butter then add in boiling water. Whisk together until smooth, set aside.
In small bowl add buttermilk, eggs, baking soda, and vanilla and whisk until combined.
In the bowl of a stand mixer fitted with a paddle attachment add flour, sugar, nutmeg, ginger, and allspice.
With mixer on low, add in cocoa mixture.
Pour in buttermilk mixture.
Slowly pour in Dr. Pepper mixture and blend until fully combined.
This batter was about 5 cups, so I evenly divided it into two 8-inch pans. (2½ cups per pan)
Bake for 30-34 minutes or until cake has pulled away from the edges and slightly cracked on top.