To make crust, combine crumbs, melted butter and sugar.
Combine well and press into bottom and sides of a 9 in pie plate. (Can use a store bought graham cracker crust.).
Combine softened cream cheese and sweetened condensed milk. Beat until smooth. Add vanilla, lemon juice and zest. Mix until incorporated and pour into crust. Smooth over top and refrigerate at least 4 hours.
After 4 hours, on low heat, heat milk until just hot (do not let it boil.).
Place chocolate chips in a blender. Add hot milk and vanilla. Place cover on blender and cover with a towel. Carefully blend chocolate and milk mixture until smooth and creamy. Allow to cool until thick but not set.
Pour mixture over cheesecake and smooth evenly over pie.
Chill until chocolate is set. Serve with whipped topping if desired.
Cooking time includes refrigeration time.
(IMPORTANT: BE VERY CAREFUL WHEN BLENDING HOT LIQUID, ALWAYS START SLOWLY.).