6 Snickers candy bars (2.07 ounces each)
3 cups sugar
3/4 cup butter (no substitutes)
2/3 cup evaporated milk
2 cups (12 ounces) semisweet chocolate chips
1 jar (7 ounces) marshmallow crème
1 teaspoon vanilla extract
Line a 9-in. square pan with foil. Butter the foil and set pan aside. Cut candy bars into 1/2-in. slices; set aside.
In a heavy saucepan, bring sugar, butter and milk to a boil over medium heat. Cook and stir until a candy thermometer reads 234 degrees F (soft-ball stage), about 3 minutes. Remove from the heat.
Stir in chocolate chips, marshmallow crème and vanilla until smooth. Pour half into prepared pan. Sprinkle with candy bar slices. Top with remaining chocolate mixture and spread evenly.
Let stand at room temperature to cool. Lift out of pan and remove foil. Cut into squares.