I'm still not comfortable sharing the flour mix that I use because I got it from the cookbook Artisanal Gluten-Free Cooking by Kelli and Peter Bronski. You really should just go buy the book for the flour mix and all of the other recipes. If you know me personally, I might be willing to share. Anyway, their mix is what I use currently and I love it. Between the mix recipe and the waffle recipe and a couple others that I've tried, I'm glad I went ahead and bought the book!
Homemade Gluten-free Baking Mix (appropriated from Kitchen Simplicity)
5 c gluten-free flour blend
1/4 c baking powder
2 T sugar
1 tsp salt
1 c butter
Whisk dry ingredients together. Cut butter into flour mixture. Store in airtight container - makes about 6 cups of mix or so.
I'm storing mine in the fridge since it's so warm around here!
Use this mix in any recipe that calls for Bisquick.