In a double boiler over medium heat, melt the chocolate chips and butter. You can alternatively melt in the microwave in 30 second intervals, stirring at each interval.
Using a hand mixer, blend your sweetener of choice, softened cream cheese, kosher salt and vanilla extract until creamy and well combined.
Pour in melted butter and chocolate and mix until combined, preferably with a silicone or rubber spatula.
Stir in unsweetened cocoa powder. Give the mix a taste and adjust sweetness if desired.
Pour the fudge mixture into the prepared pan spreading in an even layer. Optional: top with your nuts of choice and the flaky sea salt.
Refrigerate for at least an hour or freeze to set faster before slicing and serving.
Remove from the fridge and cut fudge into even squares.