Melt the butter in a skillet or saucepan over medium-high heat.
Then add minced onion, minced garlic, and thyme, and sauté until the onion wilts.
Gently whisk the flour into the onion mixture to make a roux. Stir the roux for 2-3 minutes to remove the flour's raw taste.
Gradually add ¼ or more of the stock and continue whisking until the mixture is thick and somewhat smooth.
Then, add the remaining stock, bring to a boil, reduce to low heat, and simmer until it thickens.
Add bouillon powder, Worcestershire sauce, salt, and pepper. Cook for about a minute.
Adjust seasonings to taste and the gravy thickness to the desired consistency, either with water or cornstarch. But remember that gravy thickens as it cools.