In a large bowl, whisk the eggs, cheese and seasonings together.
Add the ground turkey and mix until everything is combined (use your hands for this).
Roll the mixture into 24 individual meatballs and press 1 cube of the fontina into the center of each.
Marinara sauce
Mix the oil, tinned tomatoes, chopped herbs and minced garlic in a bowl. Season with salt and pepper to taste.
Assemble for cooking
Pour enough sauce to cover the bottom of your slow cooker and add the meatballs on top. Cover the meatballs with the remaining sauce and cook on high for 3 hours.