Preheat the oven to 175*C.
Line an 8x8-inch baking pan with foil.
Spray with cooking spray or grease foil.
Combine the chocolate chips and butter into a large microwave safe bowl.
Heat in the microwave for 1 minute then stir.
Continue heating in 30-second bursts.
Stirring between each burst, until mixture is melted and smooth.
Please be careful not to scorch it.
Let cool slightly.
In a large mixing bowl, beat eggs and sugar until light and thick.
Add in the vanilla extract, and beat.
Stir in the cooled chocolate mixture with a rubber spatula.
Then gently fold in flour until combined.
Pour the batter into the prepared baking pan.
Sprinkle a little sea salt flakes on the top of the batter.
Do not over salt it!
Bake 35 minutes or until skewers has a few moist crumbs when inserted.
Do not over-bake.
Let cool to room temperature before slicing.
Sprinkle a touch more sea salt of desired.