In a medium bowl, mix together beef, 1 ½ teaspoons salt, ½ teaspoon pepper, garlic powder, onion powder, garlic, and Dijon mustard. Do not overmix. Divide into 10 small patties. Set aside.
In a measuring cup, mix together beef broth, chicken stock, and Worcestershire sauce.
In a large skillet, add oil and heat over medium-high heat. Add in patties and cook until seared on one side, about 2-3 minutes. Flip patties and continue cooking for an additional 1-2 minutes. Remove from pan and set on a plate. Discard oil.
Add butter and sliced onions in pan. Add ½ teaspoon salt. Cook until onions are tender and just beginning to caramelize, about 8-10 minutes. Add in thyme and flour and cook for 1 minute.
Slowly whisk in broth mixture. (It will look like a paste, and bubble.) Keep whisking and adding in broth until it’s all been added. Bring to a boil, then reduce to medium to simmer.
Return patties and any juices that collected to the gravy. Continue cooking for 5-6 minutes until patties are cooked through and gravy has thickened. Taste for seasoning and adjust.
Serve hot over rice or mashed potatoes.