Melt the butter in a heavy saucepan. Stir in the evaporated milk and sugar. Bring to boil over a medium heat, stir constantly. Simmer the mixture gently, continuing to stir for about 5 minutes.
Remove from heat and add the halved hazelnuts, chocolate chips. Stir until the chocolate chips have completely melted.
Quickly pour the fudge mixture into the prepared tin and spread it out evenly, using a palette knife. Chill until firm and cut into squares. Store in an airtight container, separating the layers with baking parchment.