4 ounces 72% bittersweet chocolate, coarsely chopped; or a similar percentage dark chocolate
2 cups granulated sugar
4 large eggs
1 ounce red food coloring, or as needed for desired shade
2 teaspoons vanilla extract
1/3 cup unsweetened cocoa powder, sifted if it's lumpy
1 1/2 cups all-purpose flour
1/2 teaspoon kosher salt
Cream Cheese Swirl
2 large egg whites
8-ounce package cream cheese, very well softened
1/4 cup granulated sugar
2 tablespoons all-purpose flour
1 teaspoon vanilla extract
Preheat oven to 350°F, line a 9x13-inch pan with heavy duty aluminum foil if desired for easier cleanup, and spray with cooking spray; set aside.
To a very large microwave-safe bowl, add the cubed butter, chopped chocolate, and heat on high power for 90 seconds, or until the butter has melted and the chocolate can be stirred smooth. Heat for additional time in 15 seconds bursts if needed.
Add the sugar and whisk to combine; mixture will seem thick and granular. Add the eggs and whisk to combine.
Add the red food coloring, vanilla, and whisk (gently at first) to incorporate. Add additional food coloring as desired until the batter is as red as desired.
Add the cocoa powder and stir to incorporate. Add the flour, salt, and stir to incorporate. Turn batter out into prepared pan; set aside.
Cream Cheese Swirl
Add the egg whites, cream cheese, sugar, and beat on high with a handheld electric mixer for about 5 minutes, or until cream cheese is totally smooth and mixture has fluffed up significantly in volume.
Add the flour, vanilla, and beat to incorporate.
Drop the cream cheese mixture over the brownie batter in heaping tablespoonfuls. It seems like there is a lot of the cream cheese mixture, and there is, but after swirling it into the brownies, and baking, it's just the right amount.
Swirl gently using a knife to create a marbled effect.
Bake for about 40 to 45 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Start checking at 30 minutes, rotating your pan once midway through baking to ensure even cooking and browning. Depending on a lot of variables, it may take slightly longer than 45 minutes, do not be alarmed, just cook until it passes the toothpick test.
Brownies can be frozen for up to 4 months. (If they aren't eaten immediately).