Preheat oven to 350°F. Coat a 9x13 baking dish with nonstick cooking spray.
In a mixing bowl, combine 1½ cups of the cake mix with the flour, yeast, and warm water, beating until well blended.
Add the eggs and mix just until incorporated—don't overmix.
Pour the batter into your prepared dish and spread it evenly across the bottom.
Spoon the cherry pie filling over the batter in small dollops, distributing it evenly across the entire surface.
In a small bowl, combine the remaining cake mix with the melted butter, stirring until the mixture becomes crumbly.
Scatter this crumb topping evenly over the cherry layer.
Bake for 25-30 minutes, then transfer to a wire rack and let it cool until warm to the touch.
While the cake cools, whisk together the powdered sugar, corn syrup, and water in a clean bowl until smooth.
Drizzle the glaze over the warm coffee cake, allowing it to cascade down the sides.
Cut into bars and serve while still warm for the best experience.
Notes
Water temperature is important for yeast activation (120-130°F). Don't overmix batter after adding eggs. Distribute cherry filling evenly across surface. Add glaze while cake is warm but not hot.