Preheat the oven to 350°F (175°C). Grease an 8×8 or 9×9-inch square baking pan with butter and line the bottom with parchment paper for easy removal.
Mix the dry ingredients: In a small bowl, whisk together the flour, salt, and baking powder. Set aside.
Melt the chocolate and butter: In a medium saucepan over low heat, add the chopped unsweetened chocolate and butter. Stir constantly until fully melted and smooth. Don’t rush this step—low and slow prevents burning.
Stir in oil: Once the chocolate mixture is smooth, stir in the oil until fully combined.
Add sugar and eggs: Off the heat, add the sugar and eggs to the chocolate mixture. Stir well with a wooden spoon or spatula until the mixture is glossy and the eggs are fully blended in.
Add vanilla: Stir in the vanilla extract.
Fold in dry ingredients: Gently fold the flour mixture into the chocolate mixture until just combined. Avoid overmixing to keep the brownies fudgy.
Bake: Pour the batter into the prepared pan and spread evenly. Bake for 35–40 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).
Cool and frost (optional): Let the brownies cool completely in the pan on a wire rack. If desired, frost with chocolate sour cream frosting. They're delicious with or without!
Notes
Storage
Room Temp: Store brownies in an airtight container for 3 to 4 days to keep them soft and chewy. Fridge: Keep in the fridge for up to a week. Bring to room temp before serving for the best texture. Freeze: Freeze unfrosted brownies for up to 3 months. Wrap individually and thaw at room temp.