Preheat oven to 325 degrees F (165 degrees C). Grease and flour 18 muffin cups or use paper liners. Mix together the flour, baking soda, salt, cinnamon, nutmeg and hot chocolate mix. Set aside.
In a large bowl, cream together the butter, olive oil and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the sour milk and vanilla. Beat in the flour mixture, just until incorporated. Stir in the grated zucchini and chocolate chips. Pour batter into prepared pan.
Bake in the preheated oven for 25 to 30 minutes, or until the top of the cupcakes springs back when lightly pressed. Cool in pans over a wire rack for at least 10 minutes before removing from baking cups. They are really gooey when fresh from the oven.