01 - Preheat the oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large bowl, whisk together melted butter, sugar, and ube halaya until smooth.
03 - Add eggs and vanilla extract to the mixture, whisking until fully incorporated.
04 - In a separate bowl, sift together flour, salt, and baking powder.
05 - Gently fold the dry ingredients into the ube mixture, taking care not to overmix.
06 - In a microwave-safe bowl, melt the chocolate with 2 tablespoons of butter in 30-second intervals, stirring until smooth.
07 - Spread the ube brownie batter evenly in the prepared pan. Dollop the melted chocolate mixture on top in several spots, then use a skewer or knife to swirl it into the batter for a marbled effect.
08 - Bake for 32-36 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
09 - Cool completely in the pan before lifting out and slicing into squares.