Preheat oven to 350°F. Line a baking sheet with parchment paper. Spray lightly with nonstick spray. Set aside.
Heat the butter in a medium skillet set over medium heat. Add the onions and garlic and cook for 5 minutes, until onions soften. Cool slightly.
1 tablespoon unsalted butter, ½ cup diced onion, 3 cloves garlic
In a large bowl, combine onion mixture with ground turkey and next 6 ingredients (through cheese crackers) Use your hands to mix thoroughly, but be careful not to overmix.
1 pound ground turkey, 1 large egg, ¼ cup milk, 1 tablespoon Worcestershire sauce, 1 teaspoon Italian seasoning, ½ teaspoon kosher salt, ¾ cup finely crushed cheese crackers
Form mixture into 4 equal balls. Flatten each ball and place 1 ounce of cheese in the center. Pinch the edges to fully surround the cheese with the turkey mixture. Place loafs on prepared baking sheet.
4 ounces shredded or cubed cheese
In a small bowl, whisk the ketchup, brown sugar, and mustard together.
¼ cup ketchup, 1 teaspoon brown sugar, 1 teaspoon yellow mustard
Brush the top of each “loaf” with ketchup mixture.
Bake for 60 minutes, or until internal temperature reaches 160°F.