Preheat the oven: Set the oven temperature to 375°F (190°C).
Cook the chopped onion and minced garlic in a big pan over medium heat until they are soft (around 3 minutes).
Put the chopped jalapenos in the pan and cook them for 2 more minutes to bring out their flavors.
Prepare the roux by mixing the all-purpose flour and cooking it for 1 minute. This will make the sauce thicker later on.
Mix the liquids: Slowly pour the beef broth and heavy cream into the pan while stirring continuously to prevent any lumps from forming.
Heat the mixture until it starts to bubble gently and cook until it becomes as thick as you like.