Whisk together the unsalted butter, granulated white sugar, and light brown sugar until smooth and fluffy.
Then add the unsweetened cocoa powder, salt, espresso powder, vanilla extract, vegetable oil, and heavy cream. Whisk again and then pop in the microwave for 30 seconds. It shouldn't be hot, just warm. Whisk together to dissolve the sugar and cocoa powder.
Once smooth, add the eggs and whisk really well until combined. Beat for about a minute to help fluff up the batter.
Now add the all purpose flour and mix until you have a thick batter consistency.
Finally, mix in the chocolate chips! You can mix them into the batter or another option is to sprinkle them on top in the pan.
Transfer the batter to a 9x9 tray that's been lined with parchment paper. Smooth the top with a rubber spatula and pop in the oven at 350°F to bake for about 30 to 35 minutes.
Once they're out of the oven, allow them to cool down for about 25 minutes until set. Then cut them into individual pieces to enjoy!