Line 9x13 glass pan with parchment & then spray lightly with cooking spray. Set aside.
Put semi-sweet chocolate chips & vanilla in mixer bowl. Set aside.
Heat sugar, margarine, evaporated milk & marshmallow cream in 3 qt. heavy saucepan over medium heat.
Stir until mixture boils, boil for 5 full minutes- stirring constantly.
Remove from heat. Pour into mixer bowl over the top of the chocolate chips.
Beat with whip attachment in mixer until it's smooth & looks like silk. (if you did not use premium chocolate- it will be grainy & watery)
Transfer to your prepared dish.
Top with crumbled chocolate covered pretzels & press in
Refrigerate for at least 2 hours before cutting & serving.