Line a 8 x 8 pan with foil or parchment paper , leaving an overhang for easier removal.
Sift icing sugar and set aside.
Combine chocolate chips, butter and sweetened condensed milk in a microwave safe bowl.
Microwave on high for 2 minutes and stir until smooth.
Add vanilla extract and stir until smooth.
Add icing sugar and stir until smooth.
OPTIONAL - Stir in ½ cup of the mix ins (oreo pieces, heath bits, peanuts, walnuts etc,)
Pour into prepared 8 X 8 pan.
OPTIONAL - Sprinkle the remaining ½ cup of mix ins on top of the fudge. Press down slightly.
Cool at room temperature for at least 2 hour before moving to the fridge.
