Make the Vietnamese Coffee:
Add 3 tbsp of Trung Nguyen coffee to your phin (Vietnamese drip filter) and place it over a cup.
Pour 3 tbsp of hot water over the grounds and let them hydrate for about 1 minute.
Fill the phin with more hot water and allow it to brew until it stops dripping.
Prepare the Brownie Base:
Preheat the oven to 325°F (165°C) and place a rack in the lower third of the oven.
Butter and line an 8-inch baking pan with parchment paper.
In a small pot, brown the butter by heating it until it turns golden and develops a nutty aroma. Remove from heat.
In a separate bowl, mix the sugar, black cocoa, Dutch cocoa, and salt.
Add the browned butter to the cocoa mixture and place the bowl over a double boiler. Heat until smooth and warm enough that you can only keep your finger in the bowl for a few seconds before it gets too hot.
Remove from heat and stir in the brewed coffee and vanilla extract.
Add the eggs one at a time, whisking well after each addition.
Fold in the flour and mix until no streaks remain. Stir the batter for an additional 40 strokes to build some gluten for a slight chew. Set aside.
Make the Vietnamese Coffee Swirl:
In a bowl, mix the cream cheese, condensed milk, and sugar until smooth.
Add the egg yolk and vanilla extract, mixing until well combined.
Stir in the brewed coffee, followed by the flour, until just incorporated.
Assemble the Brownies:
Pour ⅔ of the brownie batter into the prepared pan, spreading it evenly.
Dollop the coffee swirl mixture on top of the brownie batter.
Add the remaining brownie batter in dollops over the swirl mixture.
Use a toothpick to gently create swirls, being careful not to overmix and lose the layered effect.
Bake the Brownies:
Bake for 25-29 minutes, or until a toothpick inserted in the center comes out slightly moist with a few crumbs.
Begin checking the brownies at the 24-minute mark, checking every 2 minutes until they reach the right consistency. The edges will bake faster, so focus on the center to avoid underbaking.
Cool and Serve:
Allow the brownies to cool fully in the pan before slicing. Enjoy the rich coffee-chocolate flavor!