Preheat oven to 350°F (175°C) and grease an 8x8-inch baking pan or line it with parchment paper.

In a medium saucepan over low heat, melt unsalted butter, granulated sugar, and cocoa powder together. Stir until smooth, about 5 minutes. Remove from heat and let cool slightly, then whisk in eggs one at a time.

In a separate bowl, sift together the all-purpose flour and a pinch of salt. Gradually fold the dry mixture into the chocolate mixture using a spatula.

Pour the brownie batter into the prepared pan and spread evenly. Bake for 25-30 minutes until a toothpick comes out with a few moist crumbs.

Let the brownies cool completely in the pan on a wire rack. Melt white chocolate chips in a microwave-safe bowl until smooth.

If desired, add black gel food coloring to the melted white chocolate. Use a piping bag or fork to create a spider web pattern on the cooled brownies.