Higher temp and lower rack for thicker crust in brownies?
Use your normal recipe and then leave the brownies in the oven with the heat turned off!
Start with 10 minutes and next time increase the time until you've reached the crust thickness you desire.
Why?
Leaving them in the oven with the heat turned off will keep on drying the crust (thus thickening it) until the oven cools down completely. (Don't leave them that long or you'll have a brick instead of brownies)
;-)