Ingredients
Method
Step 1 – Mix the Base
- In a large bowl, mix together melted butter and granulated sugar until combined.
Step 2 – Whip for That Crackly Top
- Add eggs and vanilla extract. Whip until the mixture turns from yellow to off-white (this is the secret to that classic crackly brownie top!).
Step 3 – Add Oil
- Mix in the vegetable oil until fully incorporated.
Step 4 – Add Dry Ingredients
- Fold in cocoa powder, all-purpose flour, cornstarch, and baking soda until the batter is mostly smooth (don’t overmix).
Step 5 – Bake the Brownies
- Pour batter into a greased, parchment-lined square pan.
- Bake at 350°F for 28–30 minutes.
Step 6 – Cool
- Let brownies cool while you prepare the frosting.
Step 7 – Make the Graham Cracker Frosting
- Beat butter on high speed for 3–4 minutes until light and fluffy.
- Add powdered sugar until thick and smooth.
- Mix in heavy cream and crushed graham crackers, then whip on high for 2 minutes.
- Finish with vanilla extract.
- Spread frosting over cooled brownies and top with mini marshmallows. (Optional: lightly toast the marshmallows!)
Step 8 – Slice & Store
- Let brownies set for 20–30 minutes before slicing.
- Enjoy fresh or store in the fridge for up to 10 days.