"Dry" Roux - anyone do this?

I love gumbo & etouffe, but I hate making roux which seems to take forever in order for me not to overcook it. Then today, I saw on TV a chef using a shortcut where he used dry roasted flour that he had already made in the oven as a substitute for roux. This seems perfect for me & would allow me a bit more consistency as well as saving time.

Does anyone do this? And does it taste pretty much the same? Do you have any tips (the chef said he did it in the oven but the net searches say to toast on skillet & watch carefully). I"m also trying to find some estimate of how much flour one needs to add (is it about the same amount) when one cooks w/ this?

hope someone out there knows.

My grandma makes her roux this way and it's delicious! Not exactly sure what her method is, but I believe she puts a thin layer of flour on a cookie sheet and puts it in a slow oven. Check and stir frequently, and store in an air-tight container.
hth!