Place chocolate chips in a heat proof bowl and set aside
Brown your butter in a saucepan over medium-low heat, stirring frequently until it develops a nutty aroma and golden-brown color (approximately 6-8 minutes). The butter will pop and sizzle, when it goes silent this is a good sign it is done. Remove from heat and immediately pour it over the chocolate chips, wait 2 minutes for the heat of the butter to melt the chocolate and then stir until smooth
In a large bowl, whisk together the granulated sugar, dark brown sugar, cocoa powder, and salt. Pour in the brown butter-chocolate mixture and whisk until combined
Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract. Finally, add the flour and gently fold until just combined - be careful not to overmix