Use a mixer (e.g. Thermomix) to shred the nut chocolate into small pieces. Then heat slowly with the milk in a saucepan while stirring until the chocolate has melted.
Remove the pan from the heat and use a whisk to mix in the softened butter and oil.
Transfer to a clean glass and store in the refrigerator. Before use, the spread should be allowed to come to room temperature so that it is smoother.