Preheat your oven to 350°F (175°C).

In a food processor, crush about 2 cups of pretzels until finely crushed. Combine them in a mixing bowl with melted unsalted butter and brown sugar, stirring well until it resembles wet sand. Press this mixture firmly into the bottom of a greased 8x8-inch pan.

Melt 1 cup of semisweet chocolate chips in the microwave in 30-second intervals, stirring in between until smooth and melted. Pour the melted chocolate over the pretzel crust, spreading it evenly with a spatula.

In a mixing bowl, beat 2 packages of cream cheese and 1 cup of light brown sugar until smooth and creamy. Gradually add in 2 large eggs, mixing well after each addition. Finally, blend in 1 cup of smooth peanut butter, 1 teaspoon of vanilla extract, and a pinch of fine sea salt until fully incorporated.

Carefully pour the peanut butter cheesecake mixture onto the prepared crust and chocolate layer. Bake for about 42 minutes, until the edges look set and the center remains slightly jiggly.

Remove the pan from the oven and let it cool at room temperature for a couple of hours. Refrigerate for at least 3 hours.

To create the ganache, heat ½ cup of heavy cream until it just begins to simmer. Pour it over 1 cup of semisweet chocolate chips and stir until smooth and glossy.

Drizzle the ganache over the chilled cheesecake bars and allow to set before slicing into squares.