In a medium saucepan over medium heat, melt the butter. Whisk in the flour, and cook, stirring constantly, until the flour turns golden brown, about 4 minutes.
While whisking, slowly pour in the broth and whisk until smooth. Stir in the onion powder. Reduce the heat to medium-low.
Simmer, stirring frequently, for about 5 to 10 minutes, until the gravy thickens enough to coat the back of a spoon. Add salt and pepper to taste. Serve immediately or keep warm until ready to serve.
Notes
Gravy can be made in advance! Refrigerate it in an airtight container for up to 2 days until you're ready to serve. It can also be frozen for up to 3 months. Let it thaw in the refrigerator for 24 hours. When ready to serve, warm it gently in a small saucepan over medium-low heat, stirring frequently.