Line the bottom and sides of an 8 1/2 4 1/2-inch loaf pan with parchment paper or foil and grease it lightly (preferably with Pam). Melt the milk chocolate in a small heatproof bowl set over simmering water, stirring until the chocolate is melted and smooth. Remove the bowl from the heat. Pour half of the milk chocolate into the prepared loaf pan and spread it evenly. Freeze for 15 to 18 minutes, until cold.
Once the layer is cold, make the next layer. In a large saucepan, combine the sugar and 1/4 cup water. Cook over low heat, stirring occasionally, until the sugar is dissolved and the liquid is clear.
Increase the heat to medium high and boil, without stirring, for 3 to 5 minutes, or until the sugar begins to turn golden brown on the edges. While gently and continually swirling the pan over the heat to even out the color, cook for 2 to 3 minutes, or until the sugar turns deep amber.
Slide the pan from the heat and slowly add the cream. Careful! It will splatter up, and the steam is hot. Stir until well blended. Add the white chocolate and salt and stir until the chocolate is melted and the mixture is smooth. Add the peanuts and stir until blended. Set aside for 5 minutes to cool slightly.
Pour the peanut mixture into the loaf pan over the milk chocolate and spread it evenly. Freeze for about 45 minutes, or until cold and firm.
Once the layer is cold, make the next layer. Reheat the remaining milk chocolate, pour it over the caramel, and spread it evenly. Refrigerate or freeze for 20 to 30 minutes, until very cold.
Using the parchment paper or foil pan liner, transfer the candy onto a work surface. Peel away the paper or foil, and place the candy on a cutting board. Using a large knife, trim off the edges and cut lengthwise into two 1 1/2-inch-wide strips. Cut each strip into 9 pieces. Store in an airtight container in the refrigerator for up to 5 days.