Line a cookie sheet or half sheet pan with parchment paper.
In a small glass bowl melt 1 cup of the chocolate chunks in the microwave, 30 seconds at a time until fully melted.
Spread the chocolate evenly over the parchment paper into a 9x13 rectangle, making sure not to spread it too thin. An offset spatula works really well here.
Cool in the fridge for 10 minutes.
In a medium bowl or the bowl of an electric mixer, add the cookie butter, confectioners sugar, and melted butter, mix on medium till combined.
Remove the chocolate from the fridge, and spread the cookie butter mixture evenly on top of the chocolate. Make sure not to spread the cookie butter over the chocolate edge.
Melt the other cup of chocolate and spread it over the cookie butter layer this time going over the cookie butter edge so that its enclosed between the chocolate.
Place in fridge for a minimum of 20 minutes, or until the chocolate has hardened.
Cut off the edges to even out the rectangle, and then cut into even squares.
Sprinkle with sea salt.
Keep in fridge.