Line an 8x12 or 9x13 baking pan,* with parchment paper and generously grease the uncovered ends.
In a large bowl, combine butter with sugar with a whisk. Add the eggs and vanilla, and combine until the eggs are fully incorporated into the mixture.
Into the same bowl, sift the flour, cocoa powder, and salt. Lightly whisk the dry ingredients into the wet ingredients until they've just been incorporated.
Fold most of the chocolate into the batter, reserving about ¼ cup to sprinkle over the top.
Pour the batter into the lined baking pan, spread it evenly with a spatula, and sprinkle the remaining chocolate chips over the top.
Bake in the preheated oven for 30 minutes or until the center of the brownies has just set.
Notes
Baking time will vary between pan sizes. An 8x12 pan will yield taller and fudgier brownies than a 9x13 pan. I recommend you check for doneness.Make these gluten-free by using a 1:1 all-purpose gluten-free flour like this one.