Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
Melt the butter in a saucepan over medium heat.
Remove from heat and stir in sugar, eggs, and vanilla until well combined.
In a separate bowl, sift together flour, cocoa powder, and salt.
Add the dry ingredients to the wet mixture and stir until just combined.
Fold in the chocolate chips.
Pour the batter into the prepared baking pan and spread evenly.
Bake in the preheated oven for 25 minutes or until a toothpick comes out with moist crumbs.
Allow to cool in the pan before cutting into bite-sized squares.
Drizzle melted chocolate on top and sprinkle with sea salt if desired.