Preheat the oven to 400 degrees F. Line an 8-by-4-inch loaf pan with parchment paper, allowing 1-inch wings to hang over the edges on the long sides.
In a large mixing bowl, toss the marzipan with the powdered sugar to coat. Add the chocolate chips and set aside.
In a food processor, combine the flour, baking powder, salt and 2 tablespoons of the sugar and pulse to combine. Add the butter cubes and pulse until the butter is the size of peas. Add this to the bowl with the marzipan.
In a small bowl, whisk together the eggs, buttermilk or cream, and extracts and add to the dry ingredients. Use a wooden spoon or spatula to stir until just combined.
Pour the mixture into the prepared loaf pan and spread it out evenly. Sprinkle the top with remaining teaspoon of sugar and bake until golden brown on top and a toothpick inserted into the center comes out clean, about 40 minutes.
Cool in the pan on a rack for 10 minutes. Using the parchment wings, remove to the rack to cool completely. Cut with a serrated knife and serve with jam.