A quarter cup of whatever solid material you use to make chicken stock would probably provide a few years’ allotment of salt, disodium guanylate, corn syrup, and other hard-to-pronounce ingredients for you, your family, and the neighbors three doors down!
The recipe is calling for 1/4-cup of liquid chicken stock. In the recipe world, no one ever refers to bouillon cubes or granules, concentrated stock, or stock base as simply “stock” or “broth.” It is always to be diluted.
Your question is a perfect opportunity to suggest making a real chicken stock (or beef stock) when you have the time, freezing it in ice cube trays, and storing the cubes in a thick freezer bag for use whenever a recipe calls for stock. Your food will taste better if you use a homemade stock.
And finally, it is intriguing to us that a recipe for broccoli and beef wants chicken stock. We would use beef stock instead.