Preheat your oven to 350ºF / 180ºC. Line a 12-cup muffin tin with paper cupcake liners.
In a large bowl mix together brown sugar, olive oil, eggs, vanilla, and buttermilk. Stir in grated zucchini, and set aside.
In a smaller bowl sift together flour, cocoa, salt, baking soda, and cinnamon.
Add the dry mix to the wet, and stir to just combine. Fold in the chocolate chunks, and spoon the mixture evenly into the prepared cupcake liners.
Bake for 25 - 30 minutes, rotating the tin once about half way through. A toothpick inserted into the middle of a cupcake should come out with only a few crumbs attached.
Let the cupcakes cool in the tins for about 5 minutes, then transfer to a wire rack to cool completely.
While they are cooling, prepare the mascarpone. In a small bowl mix mascarpone, honey, and salt together until well combined.
Using a spatula, spread a small amount of the mascarpone onto each cupcake.