Not exactly a question about the recipe, Blondies - Gluten-Free and Completely Delicious, itself, but about the whisk shown in slides 4 & 5.

Sometimes it's just the pleasure of feeling that piece of equipment in your hand...

I vote balloon.

I've been hoping that Merrill would weigh in, but in the meanwhile... I really like whisks, and I often pick up new ones. Most of which don't get much use, so I'm especially to learn from other people's experience. The double round type (if you look closely, you'll see that there are two wire spheres, one inside the other) are usually thought to be really good at incorporating air into the mixture. For these blondies, I wouldn't have thought that was so important--I would have used a more standard teardrop balloon-type whisk with thicker wire. Anyone else?

Here's what I found when I googled whisks...

http://www.feaststl.com/this-months-feast/gadget-a-go-go/article_e1e91f4c-dfdf-11df-8853-0017a4a78c22.html

Good luck!