In a medium saucepan, combine beef broth, chicken broth, beef bouillon, onion powder, garlic powder and Worcestershire sauce. Stir to combine and dissolve the spices.

Add 2-3 drops of browning liquid if a darker color gravy is desired.

In a small Tupperware, combine cold water and cornstarch. Shake vigorously until combined.

Cook gravy until it is boiling, then whisk in the cornstarch slurry. Make sure to whisk continuously while adding the slurry to ensure no lumps.

Reduce the heat to medium low and let the gravy simmer until it reaches your desired consistency and thickness. Once this has been achieved, stir in one tablespoon cold butter.

Serve immediately, or store in the refrigerator for 5 days, or freezer for 5 months.