Heat a large oven-safe skillet over medium-low heat and add the olive oil. Stir in the onions with a big pinch of salt. .Cook, stirring often, until the onions caramelize, about 30 to 40 minutes. Once the onions are golden and caramelly, transfer them to a plate. (Note: if you’re really in a rush, you can add 1 teaspoon of sugar, honey, maple syrup, etc to speed along the caramelization process. Be sure to stir often and check on the progress!)

Preheat the oven to 350 degrees F. Take half of the cooled caramelized onions and chop them up a bit - just so they easily mix into the meatballs.

In a bowl, stir together the turkey, garlic, ½ cup gruyere, all the parmesan, the breadcrumbs, parsley, thyme, salt and pepper. Add in the chopped caramelized onions. Mix until the meatballs are just combined - do not over mix!

Use your hands to form the mixture into 1-inch meatballs. It helps if you wet your hands with water before rolling. It’s okay if the meatballs are not perfect rounds!

Heat the same skillet over medium heat and add a drizzle of olive oil. Add the meatballs in a single layer and brown them on all sides - let them cook for 1 to 2 minutes, before flipping.

Once the meatballs are completely browned, fill a shaker cup or water bottle with the stock and flour. Shake it for 30 seconds. Pour the mixture into the skillet with the meatballs. Add in the remaining caramelized onions. Top the meatballs with the remaining gruyere cheese.

Bake for 20 to 25 minutes, or until cooked through (you want the internal temp to read 165 degrees F). Serve immediately! I love serving these on sourdough bread, like a meatball melt!