In a skillet over medium high heat, heat oil until it’s hot. Then add the meatballs, and sear for 3 minutes per side or until they’re brown (the meatballs won’t be cooked through, and will be cooked later, we are just searing).
Reduce the heat to medium, then to the same skillet, add butter and melt it, then add flour and whisk it with the butter and cook for 1 minute. Add the broth, and scrape off any bits stuck to the bottom and whisk until well combined. Whisk in the dijon mustard.
Return the meatballs to the skillet and reduce the heat to simmer. Cook for 6-8 minutes stirring regularly so they don’t stick to the bottom of the pan. Add the heavy cream to the gravy, and stir it in with a spatula.
Taste the sauce and adjust the seasonings to your preference (salt and pepper). Remove from heat, and garnish with fresh chopped parsley if desired. Serve with mashed potatoes, peas or broccoli, and lingonberry jam if you have it.