Heat-Treat the Flour. Spread the flour evenly on a baking sheet and bake at 350°F for 5 minutes. Let it cool completely before using to eliminate any potential bacteria.
Mix the Wet Ingredients. In a medium bowl, whisk together melted butter, brown sugar, granulated sugar, milk, and vanilla extract until smooth and creamy.
Add the Dry Ingredients. Sift the heat-treated flour, cocoa powder, and salt into the wet mixture. Stir until fully combined. The batter should be smooth and thick.
Customize. Fold in chocolate chips, nuts, or any mix-ins of your choice for added texture and flavor.
Serve & Enjoy. Scoop the edible brownie batter into a serving bowl, garnish with extra chocolate chips or a sprinkle of cocoa powder, and dig in with a spoon!