Preheat & Prepare: Preheat your oven to 350°F (175°C) and grease or line an 8-inch square baking pan with parchment paper.
Melt Chocolate & Butter: Melt the chocolate chips and butter together using a double boiler or microwave in 30-second bursts, stirring in between until smooth.
Mix Dry Ingredients: In a separate bowl, sift together the flour, cocoa powder, and salt.
Mix Wet Ingredients: In another bowl, whisk together granulated sugar, brown sugar, eggs, vanilla extract, and vegetable oil until well combined.
Combine: Gradually mix the melted chocolate mixture into the wet ingredients, then slowly fold in the dry ingredients. Do not overmix.