01 -
Preheat oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving some overhang for easy removal.
02 -
In a medium microwave-safe bowl, melt the butter. Add the granulated sugar and whisk until well combined. Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract.
03 -
Sift in the cocoa powder, then add the flour and salt. Fold gently until just combined, being careful not to overmix. Spread the brownie batter evenly in the prepared pan.
04 -
In a separate bowl, combine the chopped pecans, brown sugar, corn syrup, melted butter, egg yolk, vanilla extract, and salt. Mix until all ingredients are well incorporated.
05 -
Dollop spoonfuls of the pecan pie mixture over the brownie batter. Use a knife or toothpick to gently swirl the two mixtures together, creating a marbled effect. Don't overmix; you want distinct layers.
06 -
Bake in the preheated oven for 25-30 minutes, or until the center is set and a toothpick inserted comes out with a few moist crumbs (not wet batter).
07 -
Allow the brownies to cool completely in the pan on a wire rack before lifting out using the parchment paper. Cut into squares and serve.