Preheat oven to 350 degrees. Spray a loaf pan with cooking spray.
In a large pan, heat the olive oil over medium-high heat.
Add the peppers, shallots, garlic and red pepper flakes. Sauté for 5 - 7 minutes or until vegetables begin to soften. Remove from heat.
In a large bowl, whisk together the eggs, thyme and chives.
Add the meat, cheese, 1/2 C ketchup, 2 T balsamic vinegar and the vegetable mixture. Season with sea salt and freshly ground pepper. Mix until combined.
Spoon the meatloaf mixture into the loaf pan.
Whisk together 1 T ketchup and 2 T balsamic vinegar. Pour the glaze over the meatloaf.
Place the loaf pan on a rimmed baking sheet (to catch any overflow juices) and bake for 55 minutes to 1 hour, or until cooked through.
Remove from oven and let rest for 10 minutes before serving.
I often use Sherry Ketchup in this recipe because it creates an extra rich, decadent flavor. I love the brand Victoria Amory & Co.