Found this recipe online that may work.
It didn't specify how much beef base but one poster added this. Suggestion is to start with amount specified for one cup, then taste and adjust. Another said they used 3 bouillon cubes.
Maybe Better Than Bouillon Seasoned Vegetable Base.
Browning Sauce
1⁄2 cup sugar
1 cup hot water
beef base
Be careful while preparing this as it may sputter.
Add the sugar to a saucepan and heat on a low or medium-low heat until browned, about 5-10 minutes. When the mixture starts to get dark, take it off the heat and carefully add the water (this may sputter and you don't want to get burned).
Add the beef soup base and put back on a low heat, stirring until the water is all mixed inches
Cool and store in a disposable container.
Use a spoonful or two when making gravies, stews, sauces, meatloavs, meatballs, etc.