Preheat oven to 350°F. Spray a 9x13" baking pan with vegetable oil and line the bottom with parchment paper (see note).
Melt chocolate chips in a large glass bowl over a pot of barely boiling water. Add the boiling water, cocoa and coffee. Whisk together until smooth and allow to cool slightly. In a separate bowl, whisk together flour, baking soda and salt.
Whisk sugar, eggs and vanilla into the chocolate mixture, then slowly whisk in the oil until emulsified. Add half the flour mixture to the chocolate mixture and gently whisk to combine. Repeat with second half of flour mixture. Gently stir in the cherry pie filling. Do not overmix. The batter will be thick, like pudding.
Scrape batter into prepared pan, and smooth the top with a spatula. Bake until toothpick comes out with a few moist crumbs, 35-40 minutes. Rotate pan halfway through baking.
Let cake cool completely in the pan. Run a knife around the edges then turn onto a wire rack. Peel parchment off, and frost, if desired.
Note: The cake can also be made using two 9" round cake pans and layered. Reduce cooking time slightly.