Christmas Fudge

This is a very tempermental recipe--I can't even get it to work right sometimes!

2-1/2 cups sugar
1 cup evaporated milk
3 cups milk chocolate chips
1 lb. REAL butter
1 tsp. vanilla
1 cup chopped pecans

Combine sugar and evaporated milk in large saucepan and stir with wooden spoon over med-low heat ("3"-"4") the whole time.  Stir constantly.  After boiling starts, continue to cook and stir until you see a speck of burning. As soon as you see a speck of burning, take off of heat.  Add chocolate, vanilla and butter.  Mix with mixer until it is well-combined.  Mix in chopped nuts.  Spread into 9x13 glass baking dish, lined with wax paper or parchment.  Allow to cool.  Lift out parchment and slice into small bite-sized pieces.  Store in sealed container.