Step 1: Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper for easy cleanup.
Step 2: In a large skillet, heat the olive oil over medium heat. Add the finely chopped onion and bell pepper and cook until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant. Remove from heat and let cool slightly.
Step 3: In a large mixing bowl, combine the breadcrumbs and milk. Let sit for 5 minutes to allow the breadcrumbs to soften.
Step 4: Add the cooled onion and bell pepper mixture, ground beef, ground pork, beaten eggs, Worcestershire sauce, 1/4 cup ketchup, dried thyme, salt, and black pepper to the bowl with the breadcrumbs. Using your hands, gently mix all ingredients until just combined. Be careful not to overmix, as this can make the meatloaf tough.
Step 5: Form the meat mixture into a free-form loaf shape, about 9x5 inches, on the prepared baking sheet.
Step 6: In a small bowl, whisk together the glaze ingredients: 1/2 cup ketchup, brown sugar, yellow mustard, and apple cider vinegar.
Step 7: Spread half of the glaze evenly over the top of the meatloaf.
Step 8: Bake for 45 minutes. Remove from the oven, spread the remaining glaze over the meatloaf, and return to the oven for another 30-40 minutes, or until the internal temperature reaches 160°F (71°C) on a meat thermometer.
Step 9: Once baked, remove the meatloaf from the oven and let it rest on the baking sheet for 10-15 minutes before slicing and serving. This allows the juices to redistribute, ensuring a moist and flavorful result.