Add bacon to the skillet and cook until bacon is crispy, about 8 minutes. Using a slotted spoon, remove bacon from the skillet and place the bacon in the large bowl along with the onions. Reserve the bacon fat (leave it in the skillet).
Add ground turkey, eggs, salt, pepper, allspice and nutmeg to the onion mixture. Stir to combine. Add the reserved bread crumb mixture to the onion mixture. Stir to combine.
Line a baking sheet with parchment paper. Roll meat mixture into a 1 inch ball and place on the prepared baking sheet. Repeat with the remaining meat mixture.
Add one tablespoon butter to the reserved bacon fat in the skillet and heat over medium low heat. Working in 3 batches, place ⅓ of the meatballs in the skillet, per batch and brown on all sides. This will take about 6-8 minutes per side. The meatballs will not be cooked through. If needed, add a tablespoon of butter between batches. Line a plate with paper towels. Transfer the meatballs to the plate after they have been browned. Dab the top of the meatballs with more paper towels.
Drain fat from skillet, leaving 2 tablespoons behind. Slowly whisk in flour and stir until a paste is formed. Slowly whisk in 2 cups of chicken broth. Raise the heat to medium high and bring the broth mixture to a simmer.
Add the meatballs back to the skillet. Cover the skillet and simmer the meatballs until they are cooked through, about 15 minutes. Remove skillet from heat and whisk in the sour cream. Stir so that the sauce coats the meatballs.
Serve hot with pasta or mashed potatoes, if desired.
Recipe by The Little Chef at http://littlechefblog.com/swedish-meatballs/