Chocolate Zucchini Bundt Cake with Chocolate Glaze is so moist and decadent that nobody will ever guess that it's concealing a pound of zucchini and 100% whole wheat flour! Or if you prefer, you can bake it in two loaf pans and leave off the glaze to call it Chocolate Zucchini Bread instead.
Adjust rack to center position of oven and preheat to 350°F. Generously coat a 9- to 10-inch (12-cup) Bundt pan with baking spray (the kind that includes flour).
Using a box grater or food processor, grate the zucchini (you should end up with approximately 3 cups). Stir in 2 tablespoons sugar and place in a large colander set over a bowl. As you prepare the rest of the batter ingredients, the sugar will draw the moisture out of the zucchini. Occasionally press down on it to squeeze more water into the bowl.
Finely chop unsweetened chocolate, place in a bowl, and heat in the microwave for 30 seconds; stir. Heat in additional 15-second increments, stirring after each one, until chocolate is completely melted and smooth. Allow to cool.
In a medium bowl, whisk together whole wheat pastry flour, cocoa powder, baking soda, and salt. In a large bowl, use an electric mixer to blend together eggs, sugar, melted chocolate, melted butter, applesauce, and vanilla until smooth. Mix in drained zucchini. Turn mixer down to low and stir in half of the flour mixture, followed by all of the sour cream and then the remaining flour mixture. In a small bowl, toss mini chocolate chips with tablespoon of flour. Add to batter and mix until just incorporated, taking care not to overbeat.
Evenly pour/spread batter into prepared pan, place in preheated oven, and bake for 1 hour, or until a toothpick inserted in center comes out clean. Remove cake from the oven and allow it to rest on a cooling rack for 10 minutes before turning it out onto the rack to finish cooling.
FOR THE GLAZE:
In a small pot, melt butter over low heat. Remove pot from heat and add chocolate chips, stirring until they are melted and combined with butter. Stir in corn syrup and vanilla until smooth. Immediately pour glaze over warm cake, gently spreading it so that it trickles down sides. Allow cake and glaze to cool completely before slicing.