Preheat the oven to the temperature recommended on the box mix and prepare a 9x13-inch baking pan by lining it with parchment paper.
Prepare the brownie mix according to the directions on the package and bake for the recommended time and allow them to cool.
1 (18oz.) box Brownie mix
While the brownies are cooling, prepare the peanut butter layer by beating together the powdered sugar, peanut butter, butter, vanilla, and salt. This will have a thick consistency. Set this aside.
2½ cups powdered sugar, 1½ cup peanut butter, ½ cup salted butter, ½ teaspoon vanilla extract, ¼ teaspoon salt
Next prepare the ganache by measuring the chocolate into a medium-sized glass bowl (you will need a lid or plate that will cover this) and set this aside.
2 cups semisweet chocolate chips
Melt the butter over medium heat in a small saucepan. When the butter is melted, whisk in the cream constantly while increasing the heat to medium-high. Cook this until it just starts forming bubbles.
2 Tablespoons salted butter, 1 cup heavy cream
Immediately pour the cream mixture over the bowl of chocolate and cover it with the lid. Let this sit for 5 minutes.
Remove the lid and stir the chocolate and cream mixture until thick and smooth.
Let the ganache cool and thicken slightly. Just stir it up again when you are ready to spread it.
Once the brownies have cooled, top them with the peanut butter mixture by dropping spoonfuls of it on the brownies, then using a rubber spatula to smooth it out and cover completely.
Pour the ganache on top of the peanut butter layer and smooth it out.
Place the buckeye brownies into the fridge for at least 30 minutes to allow them to cool and set for easier cutting.