Line a 10 x 5 loaf pan with parchment paper so that there’s some overhang over the edges. Lightly spray with nonstick cooking spray.
Make the glaze: Combine all the glaze ingredients in a small saucepan and stir well. Bring to a very gentle simmer over medium-low heat for 5 minutes, until slightly thickened. Set aside to cool.
Preheat an oven to 375 F.
Moisten the breadcrumbs. In a large mixing bowl, combine the bread crumbs, beaten eggs, and milk or half/half and stir well to combine. Let this mixture sit for 10 minutes.
Saute the onions and garlic. In the meantime, melt 2 tablespoons of butter in a medium skillet over medium heat. Once the butter is melted and foamy, add the onions and saute for 4-5 minutes, until the onions are starting to brown. Add the garlic and cook for another 2-3 minutes. Set aside to cool slightly.
Mix the meatloaf. Add the sautéed onions and garlic and any juices from the pan to the mixing bowl with the breadcrumb mixture. Add the chopped parsley, paprika, marjoram, sage, Worcestershire, salt, pepper, and dijon mustard and stir to combine. Add the ground turkey and mix gently by hand just until everything is well-mixed and the ingredients are evenly streaked throughout the meat mixture.
Bake. Press the meatloaf into the prepared baking pan, making sure to press the meat in tightly to remove any air bubbles. Spread ½ of the glaze on top of the meatloaf. Place on a baking sheet and transfer to the oven for 40-45 minutes, until the center of the meatloaf reaches 160 F.
Rest, then slice. Let the meatloaf rest in the pan for about 30 minutes, until just firm enough to handle. Use the parchment paper to lift the meatloaf from the pan. Slice the meatloaf and serve with the remaining sauce on the side.