Preheat your oven to 350°F (175°C) and prepare a baking dish.
In a large mixing bowl, combine the cocoa powder, almond flour, erythritol, and salt.
In a separate bowl, whisk together the melted coconut oil and vanilla extract.
Pour the wet mixture into the dry ingredients and mix until well combined.
If using, fold in the chopped nuts or seeds at this stage.
Spread the chocolate mixture evenly into the prepared baking dish.
Bake in the preheated oven for about 20-25 minutes.
Allow the chocolate to cool completely before slicing into squares.