Heat 2 tablespoons of olive oil in a skillet over medium-high heat. Sprinkle the cube steaks with kosher salt and freshly ground black pepper. Cook for about 8 to 10 minutes, turning to brown both sides; remove the steaks to a plate and set aside.
Add the butter to the skillet and place it over medium heat. When the butter stops foaming, add the minced shallots and mushrooms. Cook until the mushrooms are golden brown. Add the garlic and continue cooking for 1 minute. Add the thyme and flour to the skillet; stir until well blended. Continue cooking for 2 minutes. Gradually add the beef stock and continue cooking until thickened. Taste and adjust seasonings.
Add the steaks back to the mushroom and gravy mixture and heat through.