Heat the oven to 390 degrees F (200 degrees C). Grease a muffin tin or place paper muffin cups.
Pour the bran into a large bowl and sift in the flour, baking powder and baking soda
Add the the walnuts or pecans and lightly mix through with your fingers.
Heat the golden syrup in a small bowl in the microwave until it is quite runny. Add the milk and egg to the syrup and beat together. Add to the dry ingredients in the large bowl and stir together carefully but quickly, stopping before it all looks properly mixed. Do not to overmix or the muffins will look and feel like hockey pucks.
Half fill each muffin mold with the mixtures. Using a wet teaspoon make small holes in the top of each muffin. Carefully spoon a teaspoon of Nutella into each hole and cover the filling in each muffin completely with the remaining muffin mixture. Bake for 10 to 15 minutes, until the muffins spring back when lightly pressed.