Best-Ever Turkey Gravy

Melt turkey fat in a small skillet over medium. Add flour; cook, whisking constantly, until mixture turns golden brown, 5 to 6 minutes. Gradually add 3/4 cup Rich Turkey Broth, whisking constantly, until smooth. Remove roux from heat; cover to keep warm. Bring remaining 3 1/4 cups Rich Turkey Broth to a boil in a large stockpot over high. Whisk roux into boiling stock until smooth. Reduce heat to medium-low; simmer, whisking often, until mixture thickens and no floury taste remains, 5 to 6 minutes. Stir in thyme, salt, and pepper.