Preheat the oven to 350°F (175°C). Lightly grease an 8-inch oven-safe skillet with butter or nonstick cooking spray.

In a mixing bowl, whisk the melted butter and granulated sugar until well combined. Add the eggs and vanilla extract, then whisk until the mixture looks smooth and glossy.

Add the flour, cocoa powder, and salt. Gently stir with a rubber spatula until the dry ingredients are just incorporated. Avoid overmixing, as this can make the brownie dense or cakey.

Fold in the chocolate chips, spreading them evenly throughout the batter.

Transfer the brownie batter to the prepared skillet and smooth the top with a spatula. Bake for 20 to 25 minutes, or until the edges are set and the center is still slightly soft. A toothpick inserted into the middle should come out with a few moist crumbs rather than completely clean.

Remove the skillet from the oven using oven mitts and let the brownie rest for 5 to 10 minutes. The skillet will remain hot, so place it on a heat-safe surface before serving.

Add scoops of vanilla ice cream over the warm brownie and serve straight from the skillet. Enjoy while the brownie is still warm and the ice cream begins to melt into the chocolatey center.