Step 1

Line an 8-inch square baking pan with a nonstick aluminum foil or regular foil, greased with cooking oil spray. Set the pan aside.

Step 2

Place a small, heavy-bottom sauce pan on the stovetop and place the chopped butter in it. Melt the butter over medium-low heat.

Step 3

Reduce the heat to low, and add the brown sugar. Mix to combine and continue to stir as the brown sugar begins to melt into the butter.

Step 4

Add the peanut butter, and mix again to combine well. The mixture will be much thinner.

Step 5

Remove the pan from the heat and set it aside to cool briefly.

Step 6

Sift the confectioners’ sugar into a large mixing bowl. Create a well in the center of the sugar with a mixing spoon.

Step 7

Add the melted peanut butter mixture to the bowl, and mix until well-combined.

Step 8

The mixture will be thick. Keep pressing down with the bowl of your mixing spoon to ensure all the confectioners’ sugar is absorbed.

Step 9

Scatter the peanut butter mixture evenly in clumps in the prepared baking pan. Using a spatula, press it down into an even layer.

Step 10

Cover the mixture with a small piece of unbleached parchment paper or plastic wrap. Press down evenly with your hands to create a single, even layer. Set the pan aside.

Step 11

Place the chopped chocolate or chocolate chips in a medium-sized, heat-safe bowl or Pyrex measuring cup.

Step 12

Bring the cream to a simmer over low heat on the stovetop (or in the microwave, on low power) and pour over the chocolate.

Step 13

Allow the mixture to sit for about 1 minute before stirring until smooth. The chocolate should melt fully.

Step 14

Pour the chocolate ganache over the peanut butter layer in the pan, and bang the pan flat on the counter a few times to break any large air bubbles.

Step 15

Allow the chocolate ganache to set for about 5 minutes before sprinkling with the optional coarse salt.

Step 16

Chill the pan in the refrigerator until set, at least 2 hours.

Step 17

Using a sharp knife, slice into 9 larger or 12 smaller square bars and serve chilled.