In a large mixing bowl combine Buttermilk Pancake Mix, milk, eggs, sugar, and melted margarine or butter. Stir just until combined but still slightly lumpy. Stir in chocolate, chocolate pieces, and the 1/2 cup walnuts or pecans.
Heat a lightly greased griddle or heavy skillet over medium heat until a few drops of water dance across the surface. Reduce heat to medium-low. For each pancake, pour a scant 1/4 cup batter onto the hot griddle. Spread batter into a circle about 4 inches in diameter.
Cook over medium-low heat until pancakes are golden brown, turning to cook second sides when pancake surfaces are bubbly and edges are slightly dry (about 1 to 2 minutes per side). Top with a few marshmallows after turning to cook second sides.
Serve immediately drizzled with hot fudge topping. If desired, sprinkle with additional nuts. Makes about 16 pancakes.