legend - you would use the drippings from whatever you were cooking in place of the fat - in your case it would be the butter. Sometimes you have to remove some of the drippings from the pan or you will end up with waaaay too much gravy. Add the flour directly to the drippings (pan is placed over either 1 or 2 burners, depending on the size. Add flour and take it from there. Once it has cooked for the 3 minutes you can then add your liquid. In the case of my Thanksgiving turkey I add water AND a bit of milk. The flavor will be more intense from the drippings. Let it cook for the flavors to come together. Check for seasonings.
To your experiments try adding a bit of poultry seasoning too. You'll be surprised what it does. Also, instead of ALL chicken broth try a bit of milk too.
Don't you love experimenting with food?
If you do use the slurry method just be sure to cook it for the 3 minutes, just like when adding the flour.