Preheat oven to 350°F / 175°C (180°C fan-forced).

Place 3 large eggs in a medium saucepan, cover with cold water by 1 inch (2.5cm), and bring to a rolling boil. Once boiling, cover, remove from heat, and let sit for 12 minutes. Transfer to an ice bath to cool completely, then peel. (This step is optional — omit if you prefer a traditional meatloaf.)

Heat 1 tablespoon olive oil in a large non-stick skillet over medium heat. Add the diced onion, celery, mushrooms, and all the peppers. Sauté for 6-8 minutes, stirring occasionally, until softened and any liquid from the mushrooms has evaporated. Set aside and allow to cool to room temperature before adding to the turkey.

Place meat in a large mixing bowl, add the beaten egg, breadcrumbs, ketchup, cranberries, carrots, sage, salt, pepper, cayenne pepper, and the cooled sautéed vegetables. Mix well by hand.

Lightly grease a 9x5 inch (23x13cm) loaf pan or baking dish with cooking spray or a thin layer of olive oil. Press half of the meat mixture into the pan. Arrange the peeled hard-boiled eggs in a row down the centre, then cover with the remaining mixture, pressing gently to seal around the eggs.

Pat gently to smooth out evenly.

Bake for 50-60 minutes, checking after 40 minutes. If liquid has pooled around the sides, carefully drain it off (or reserve it for gravy) and return the meatloaf to the oven. The meatloaf is done when an instant-read thermometer inserted into the thickest part (avoiding the eggs) reads 165°F / 74°C.

Remove from the oven and allow to rest for 15 minutes before slicing. Internal temperature should reach 165°F / 74°C for food safety.