Preheat your oven to the temperature specified on the brownie mix box (typically 350°F). While the oven heats, line a 9x13-inch baking pan with parchment paper or foil, leaving some overhang on the sides for easy removal. Lightly grease the paper with a small amount of oil or cooking spray to prevent sticking.

Remove the cream cheese from the refrigerator to bring it to room temperature (around 70°F) while you work—this ensures it blends smoothly without lumps. In a large mixing bowl, combine the brownie mix, cocoa powder, and sea salt. Whisk these dry ingredients together for about 30 seconds to break up any lumps in the brownie mix and evenly distribute the cocoa powder and salt throughout.

In a separate bowl or measuring cup, whisk together the hot water, oil, and vanilla extract until well combined. Add the softened cream cheese to this wet mixture and whisk vigorously for about 1-2 minutes until the cream cheese is fully incorporated and the mixture is smooth—this creates a richer, more fudgy texture in the final brownies. Don't worry if a few tiny cream cheese streaks remain; they'll disappear during baking.

Pour the wet ingredient mixture from Step 3 into the dry ingredients from Step 2 and fold together with a spatula until just combined—about 15-20 strokes. The batter should be thick and fudgy-looking; don't overmix as this can make brownies tough. I like to give the batter a final stir with a wooden spoon to ensure no dry pockets remain, then pour everything into your prepared pan. Use an offset spatula or the back of a spoon to gently spread the batter into an even layer.

Place the pan in the preheated oven and bake for 50-55 minutes, or according to the time on your brownie mix box. The brownies are done when a toothpick inserted in the center comes out with just a few moist crumbs—they should not be completely dry. Since we've added cream cheese and extra cocoa powder, the baking time may be on the longer end of the range.

Remove the brownies from the oven and let them cool in the pan for at least 30 minutes before cutting—this allows them to set properly and makes slicing cleaner. For easier removal and cutting, you can refrigerate them for 1-2 hours until fully cooled. Using the parchment overhang, lift the entire brownie block out of the pan and cut into squares with a sharp knife (wiping between cuts keeps edges clean).