Add the butter to a 2-quart pot. Melt over medium-high flame.

While stirring the melted butter with a wooden spoon or whisk, sprinkle the flour into the pot. Season with salt and pepper. Keep stirring constantly, cooking until the flour mixture is deeply browned, about 4 minutes.

Slowly whisk in the stock, and I mean slowly. If you dump it all in at once, you’ll end up with lumps. Once all the stock has been stirred in, it’ll be on the thin side. Don’t fret. Keep stirring, constantly. Really, I mean this—if you let this go without stirring, you’ll get lumps. Gravy is something you really don’t want to multi-task.

Continue cooking the gravy until it thickens to your liking. 6 to 7 minutes is the sweet spot for me. Taste for seasoning, adding more salt and pepper as desired.

Remove from heat. It’ll continue to thicken as it sits, and cools. Serve immediately, or store in a container, then heat over low flame when ready to serve. May be made up to 3 days in advance.