Yes, you can use flour and fat (i.e. butter, oil) in equal proportions to make a roux. I usually use butter. Take two tablespoons of butter and melt it in a pot, add two tablespoons of flour to it. Mix the two together an let it cook for about 30 seconds, but make sure it doesn't scorch. Then add the room temperature broth to it, whisking it into the roux while you pour. When it starts to boil is should begin to thicken. Make sure you stir it occasionally. Also, I suggest adding a teaspoon of dried thyme, a small dried bay leaf, pepper, and maybe a clove of garlic to it while it simmers. Good luck!