Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 8 inch cake pans. Make sour milk by combining milk and vinegar. Set aside.
Sift together the flour, sugar, cocoa powder, baking soda, baking powder and salt. Set aside. In a large bowl, whisk together the eggs, oil, coffee and vanilla. Stir in the sour milk. Gradually beat in the flour mixture, mixing just until incorporated.
Pour batter into prepared pans. Bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow cake layers to cool completely before filling.
To make the cherry filling: Combine the cherry pie filling and cherry liquor. Refrigerate cherry mixture until chilled, then fill cake.