Preheat & Prep. To start, preheat the oven to 350 degrees F. Line an 8x8 metal baking pan with parchment paper. (Metal works much better than glass or ceramic!)
Melt. In a medium microwave-safe bowl, combine 1/2 cup chocolate chips, the butter, and the oil. Melt in 20-30 second intervals, stirring in between each interval until chocolate is smooth and glossy.
Whip Sugar & Eggs. In a large mixing bowl (ideally glass), combine sugar, brown sugar, and eggs. Use a hand mixer to beat the eggs 5-6 minutes on medium speed, or until doubled in volume and very light in color. When you lift the beaters out of the mixture, you should be able to see the batter drizzle down in a smooth stream and land on the surface before dissolving. Do NOT rush this step, or the sugar won't dissolve properly and the brownies won't have the glossy top crust we're going for. Do the full 5-6 minutes!
Add Chocolate Mixture to Egg Mixture and use a spatula to stir until combined.
Mix In Vanilla & Red Dye and stir to combine. At this point, the batter should be smooth and bright red. (For VERY red brownies, use a full 3 teaspoons. For brownies like mine that are more red on top and fudgy in the center, use 2 teaspoons)
Sift In Dry Ingredients. Use a fine mesh sieve or sifter to sift in cocoa powder, gluten-free flour, and salt. Stir until almost fully combined with just a few dry patches left.
Fold In The Chocolate Chips. Then, use your spatula to gently fold in the remaining 2/3 cup chocolate chips and mix until *just* combined with the chocolate chips evenly distributed and no floury patches remaining.
Transfer Brownie Batter To Pan and use an offset spatula to smooth the surface of the brownies as evenly as you can.
Bake Brownies at 350 degrees F. for 30-35 minutes, or until the top is glossy and set and a toothpick inserted in the center comes out with some moist crumbs (but not glossy wet batter).
Cool Completely Before Slicing. Remove the brownies from the oven and let them cool on a wire rack until completely cooled before slicing for best results. (You can speed this process up by chilling them in the fridge before slicing--this will also help you get neater cuts!)
Serve & Store. Enjoy cooled brownies right away, or store in an airtight container at room temperature 2-3 days or in the freezer up to 2 months.