Step 1: Prepare the Nougat Layer

1. Heat the Sugar Syrup: In a medium saucepan, combine the granulated sugar, corn syrup, water, and salt. Heat over medium heat, stirring until the sugar dissolves. Bring the mixture to a boil and let it cook until it reaches a soft ball stage (about 235°F to 240°F or 113°C to 115°C on a candy thermometer).

2. Beat the Egg Whites: While the syrup is heating, beat the egg whites with a hand mixer or stand mixer until stiff peaks form.

3. Combine the Syrup and Egg Whites: Once the syrup reaches the correct temperature, slowly pour it in a thin stream into the egg whites while continuing to beat on high speed. Be careful not to pour the hot syrup directly onto the beaters.

4. Finish the Nougat: After all the syrup is added, continue to beat the mixture until it becomes thick and glossy. Stir in the vanilla extract.

5. Add Rice Cereal and Powdered Sugar: Gently fold in the powdered sugar and the crispy rice cereal, making sure everything is evenly distributed.

Step 2: Assemble the Candy Bar

1. Prepare the Pan: Line a baking sheet or a large pan (about 9×13 inches) with parchment paper.

2. Spread the Nougat: Spread the nougat mixture evenly in the pan, pressing it down gently to create an even layer.

3. Add the Peanuts: Sprinkle the roasted peanuts on top of the nougat and press them lightly into the nougat to ensure they stick.

Step 3: Coat with Chocolate

1. Melt the Chocolate: In a heatproof bowl, melt the milk chocolate with the coconut oil in the microwave in 30-second increments, stirring between each until smooth and fully melted.

2. Pour the Chocolate Over the Nougat: Pour the melted chocolate over the nougat and peanuts, spreading it evenly with a spatula to completely cover the candy bar.

3. Set the Candy Bar: Refrigerate the candy bar for at least 2 hours or until the chocolate hardens completely.

Step 4: Slice and Serve

Once the chocolate is fully set, remove the candy bar from the refrigerator and carefully cut it into slices or bars of your desired size.