No-bake cookies are always a favorite for a variety of reasons. You don’t have to heat up the oven and stand watch to make sure the cookies don’t burn. A new baker will get excited after successfully making a no-bake recipe, and then venture on to more challenging recipes. If your novice baker is trying this recipe, keep a careful eye out as she combines the cream and sugar; you don’t want it to boil. These gooey bars will be your new favorite no-bake cookie. Serve chilled for less mess.
Line a 9-inch square baking pan with parchment paper, allowing parchment to extend over sides of pan. Grease paper.
Combine heavy cream and powdered sugar in a small saucepan. Bring to a simmer over medium-low, stirring occasionally. (Do not bring to a boil.) Place chopped chocolate in a medium bowl. Pour cream mixture over chocolate; let stand 1 minute. Gently stir mixture until chocolate melts and mixture is smooth. Stir in vanilla.
Combine caramels and evaporated milk in a saucepan over medium-low. Cook, stirring often, until caramels melt and mixture is smooth, 9 to 10 minutes. Remove from heat; let stand 10 minutes.
Place 1 layer of graham cracker sheets in bottom of prepared pan, breaking crackers to fit as needed. Pour one-third of the caramel mixture over crackers. Using an offset spatula, smooth caramel to edges of pan. Pour one-third chocolate mixture over caramel; smooth chocolate to edges of pan. Repeat layers2 times with remaining graham cracker sheets, caramel mixture, and chocolate mixture, ending with chocolate. Sprinkle chopped toffee candy bars over top. Chill, uncovered, 4 hours or overnight.
Lift toffee bar mixture from pan using parchment. Trim edges if necessary. Cut into 16 pieces. Serve chilled.