Make the Brownie Batter:
Preheat oven to 350F. Line an 8-inch square pan with aluminum foil leaving overhang and spray with cooking spray, or grease and flour the pan; set aside.
To a large microwave-safe bowl, add the butter, chocolate, and heat on high power to melt, about 2 minutes. Stop to check and stir after 1 minute. Heat in 15-second increments until chocolate has melted and mixture can be stirred smooth. Allow mixture to cool momentarily before adding the eggs so they don’t scramble.
Add the eggs, sugar, vanilla, optional coffee, optional espresso granules (neither make brownies taste like coffee and both enhance and round out the chocolate flavor), and whisk vigorously to combine.
Add the flour, salt, and stir until smooth and combined without overmixing.
Turn batter out into prepared pan, smoothing the top lightly with a spatula as necessary; set aside.
Make the Cream Cheese Layer:
To a medium bowl, add the cream cheese, egg, sugar, and beat with a handheld electric mixer on high speed for about 2 minutes, or until mixture is smooth. Stop to scrape down the sides of the bowl as necessary.
Add the white chocolate chips and stir to combine.
Turn mixture out over the brownie layer in heaping tablespoon-sized dollops, leaving a bare 1/2-inch perimeter around the edges (the cream cheese is prone to burning if you add it right up to the edge so leave some space). Take your time and evenly smooth the dollops together to form an solid layer.
Assemble and Bake the Brownies
Evenly sprinkles the Oreos, chocolate chips, and bake for about 43 to 45 minutes, or until brownies are done. The toothpick test is tricky since you’ll hit melted chocolate chips and soft cream cheese, but test a few patches and when inserting the toothpick into the deepest brownie layer, it should feel ‘thick’ and set and not runny. Allow brownies to cool uncovered on a wire rack for about 2 hours.
Cover with foil and refrigerate for at least 3 to 4 hours (I prefer overnight) before slicing and serving. The cream cheese needs to be chilled and set before slicing. Brownies will keep airtight in the fridge for up to 1 week. They’re best served chilled.