Combine the stock and the seasoning packets in a microwave-safe bowl or measuring cup. Heat for 1 minute and stir. Repeat until seasoning packets are dissolved.
Melt the butter in a saucepan over medium-high heat. Add the flour, onion powder, thyme, sage, and rosemary and cook for 1 minute to cook the flour. Slowly whisk in the stock until smooth and bring to a boil. Reduce to a simmer and cook, whisking, until smooth and thick, about 1 minute. Add salt and pepper to taste.
Remove from heat and serve immediately.