In a mixing bowl, add the ground turkey, panko, egg, dried minced onion, parsley, salt, nutmeg, allspice, garlic powder, and pepper and mash together until well combined. With clean hands, roll the meat mixture into 12 evenly sized meatballs.
Drizzle the olive oil into a large saute pan or skillet and bring over medium heat. When the oil is hot, add the meatballs in a single layer with a bit of space in between them. Cook, flipping them every 1-2 minutes to brown all sides, for 8 minutes. Cover the pan and reduce the heat to medium-low. Cook the meatballs covered for an additional 2-4 minutes until cooked through. Remove the meatballs to a side plate and cover with aluminum foil to keep warm.
Add the butter to the pan and bring over medium-low heat until melted. Add the flour and whisk the flour and butter together until combined (it will become sort of like a paste). Whisk in the broth a little at a time to combine it smoothly. Add the Worcestershire sauce, mustard, bouillon, dried parsley, and paprika and whisk into the sauce. Bring the mixture to a boil, stirring regularly, and then reduce the heat to low to simmer. Simmer uncovered for a few minutes until the sauce thickens. Remove from heat and whisk in the sour cream until smoothly combined. Add the meatballs back in and stir to coat. Return to low heat for 1-3 minutes, stirring occasionally, until the meatballs are heated through.