Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking pan or line it with parchment paper, leaving an overhang for easy removal later.
In a microwave-safe bowl or over low heat on the stove, melt the unsalted butter. While it’s still warm, stir in the instant coffee granules and hot water until fully dissolved. Set aside to cool slightly.
In a large bowl, whisk together the granulated sugar and eggs until pale and slightly thickened. Stir in the vanilla extract. Slowly pour in the butter and coffee mixture, stirring continuously to combine.
In a separate bowl, sift together the all-purpose flour, cocoa powder, and salt. Gradually fold the dry ingredients into the wet mixture just until no streaks of flour remain. Avoid overmixing to keep the brownies tender.
Fold in the semi-sweet chocolate chips gently, distributing them evenly throughout the batter.
Pour half of the brownie batter into the prepared pan and smooth it out. Dollop half of the dulce de leche over the batter in spoonfuls. Pour the remaining brownie batter over the top, then add the rest of the dulce de leche in dollops. Using a toothpick or skewer, swirl the caramel through the batter to create a marbled effect.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted near the center comes out with moist crumbs but not wet batter. The edges should be set and slightly pulling away from the pan.
Allow the brownies to cool completely in the pan on a wire rack. This step is crucial for the brownies to set properly and for the caramel to thicken. Once cool, lift the brownies out using the parchment paper overhang, cut into squares, and enjoy!