Preheat oven to 350 degrees F (175 degrees C). Line 2 baking sheets with parchment paper.

Mix flour, cocoa powder, baking soda, and salt together in a bowl.

Combine 1/2 cup plus 1 1/2 tablespoon sugar and butter in a large bowl; beat with an electric mixer until light and fluffy. Beat in eggs one at a time. Fold in flour mixture until dough comes together; mix in vegetable oil and milk. Fold milk chocolate and marzipan into the dough.

Drop spoonfuls of the dough on the lined baking sheets.

Bake in the preheated oven until edges are browned, about 13 minutes. Cool on the baking sheets for 5 minutes. Transfer to a wire rack to cool before serving.