Brownies are typically done when you insert a toothpick and it comes out with some moist crumbs and/or a tiny bit of thick batter (the latter could be the melted chocolate chips). If the batter is liquidy or runny, though, the brownies need about 5 more minutes in the oven. If a toothpick comes out clean, the brownies sadly have been baked for too long. That's because the brownies will continue to bake during cooling. The end result will be brownies that are a bit dry. To avoid this possibility, I like to check the brownies 5 minutes before I think they're going to be done. Especially when I try out a new recipe.