For the candy bars: Spray the bottom and sides of an 8-inch square pan with cooking spray and line with parchment paper that hangs over the edge of the pan by 1 inch.
Add 1 1/2 cups chocolate chips and 1 1/2 teaspoons coconut oil to a heatproof glass bowl and place the bowl over a simmering pot of water. Let cook, stirring the chocolate, until it has melted completely, about 5 minutes. Pour into the prepared pan, covering the bottom. Place in the freezer until set, 1 to 2 hours.
Mix together the powdered sugar, marshmallow creme, peanut butter and milk in a medium bowl until it has a soft, doughlike consistency (this mixture is incredibly sticky, and you may need to use your hands). Remove the pan from the freezer, then wet your fingertips and press the marshmallow filling down over the chocolate in an even layer. Sprinkle the peanuts on top and press lightly into the filling. Set aside.
Add the caramels and cream to a small saucepot and cook over low heat, stirring, until the caramels are melted, 5 to 8 minutes. Spread the caramel over the marshmallow filling and place in the refrigerator for 5 minutes.
Meanwhile, melt the remaining 1 1/2 cups chocolate and 1 1/2 teaspoons coconut oil in a heatproof bowl over simmering water. Spread the chocolate over the top of the caramel, then place back in the refrigerator until chocolate is fully set and hardened, about 1 hour.
Using the parchment, pull the candy out of the pan, then run a knife under warm water and cut into 14 bars. Cut 6 of the bars into small chunks to be used in the salad. (Refrigerate the remaining bars for another use.)
For the pudding: Meanwhile, combine the flour, granulated sugar and salt in a medium saucepan. Whisk in the egg yolks, then the heavy cream. Cook over medium heat, stirring constantly, until it's thickened and coats the back of a spoon, 5 to 8 minutes. Stir in the vanilla and pour the mixture into a heatproof bowl. Cover with plastic wrap pressed against the surface of the pudding. Refrigerate until cooled, about 1 hour or up to overnight.
For the salad: Add the cream and powdered sugar to a large bowl and beat with an electric mixer until stiff peaks form. Reserve 2 cups whipped cream in a separate bowl for the topping. Fold the pudding into the remaining whipped cream, then gently fold in the apple slices and candy bar pieces. Serve the salad in individual glass jars or bowls garnished with dollops of whipped cream and sprinkles.