Put all the meatloaf ingredients in the bowl of a stand mixer fitted with the paddle attachment (or a large mixing bowl if doing by hand.) Note: I like to break apart the meat as I add it to the bowl, and intersperse the other ingredients to get a head start on mixing. Over mixing can result in a tough meatloaf.
Blend the mixture until all the ingredients are evenly incorporated.
Line a baking sheet with heavy duty foil and form the meat mixture into a oval loaf, about 6x10 and approximately 3 inches high. You want it to be more or less evenly thick and wide so it cooks at the same rate throughout. So basically a squat oval shape. Note: If you are making your loaf ahead of time, just wrap the loaf in plastic and refrigerate for up to 24 hours. When ready to bake let the meatloaf sit on the counter for an hour to come up to temperature before baking.
Slide the meatloaf into your preheated oven and bake for about an hour and 15-20 minutes, or until the internal temperature is 155F (it will continue to rise as it sits to reach the safe temp of 165F.) Let sit, loosely covered with foil, for 5-10 minutes before slicing.
While the meatloaf is cooking, prepare the gravy. Melt the butter in a medium saucepan and stir in the flour. Stir over medium heat for a couple of minutes. Note: Swedish gravy is supposed to be pale, so I don't let this take on any color, but if you love a deeper color in your gravy you can let this roux get nice and brown.
Slowly whisk or stir in the broth, Worcestershire sauce, soy sauce, salt, white pepper, and nutmeg. Cook, stirring almost constantly, until it comes to a boil and has thickened a bit.
Take off the heat and let sit for a minute or two to cool down, then stir in the sour cream. If you need to reheat the gravy, be sure to do it gently, and don't bring it to a full boil again, or the sour cream can split.
Serve the meatloaf with the gravy and sprinkle the parlsey on top. Serve extra gravy tableside. Don't forget the Lingonberry jam!