Totally doable. For one thing, it helps if you bake your brownies in a glass dish. Seems to make them a little tougher, denser, than regular brownies. Also, I love using an actual Brownie Pan, which is an 8x11 inch pan or dish. You can find them at most kitchen stores, places like Marshall's or Kohl's carry them, too. Your brownies will spread out more, and it helps eliminate that "underdone" texture that you don't like. And finally, you can either bake your brownies a couple of minutes longer, or let them cool in the hot pan longer - that toughens them up a bit, too.

Try this recipe: https://houseofnasheats.com/thick-fudgy-chewy-ultimate-brownies/ I like it because the brownies are that chewy consistency you like, too.