Yes, I did forget to mention that with pyrex you need to lower the temp by 25 degrees. I have also tried this in the past and it does help with less dense baked goods, like a cake with eggs and baking powder and/or baking soda. But brownies, at least fudgey ones are dense in the center already. And although I've not baked the Hornets Nest Cake, from the sounds of the ingredients, I would imagine that it is similar in texture to a fudgey brownie and that's why I suggested trying an aluminum pan. The heat is distributed more evenly and I get better results with recipes like this one using an aluminum baking pan. I've been baking for over 50 yrs, I bake something every week and not to be immodest, most people think I'm pretty good at it. But by all means give the pyrex a try at the 25 degree lower temp., if it works, great, if not why not give my suggestin a try.
Eddie
Eddie