Preheat oven to 400°F and line a baking sheet with parchment paper or foil.

Heat 1 teaspoon olive oil in a small skillet over medium heat. Add the minced garlic and shallot and cook for 1–2 minutes, just until softened and fragrant. Remove from heat and let cool slightly.

In a medium bowl, whisk together the egg, milk, tomato paste, Italian seasoning, salt, and pepper. Stir in breadcrumbs, Parmesan, sun-dried tomatoes (if using), and herbs. Add the cooled garlic-shallot mixture and stir to combine, then set the pan aside for the glaze.

Add the ground beef and pork blend, along with half of the mozzarella. Mix gently with your hands until just combined. Do not overwork. Shape the mixture into a small loaf about 6x4x2 inches on the prepared baking sheet or make two mini loaves if you want them to cook a little faster.

Heat a small skillet over medium-low heat and add the olive oil. Stir in the tomato paste and cook for 1–2 minutes, pressing it into the pan so it darkens slightly and smells sweet and caramelized. Turn off the heat and whisk in the balsamic vinegar, water, crushed red pepper flakes (if using), and a pinch of salt and pepper until smooth. The glaze should be thick but brushable. Brush half the glaze over the top.

Bake for 20 minutes, then brush with the remaining glaze and sprinkle the remaining mozzarella on top. Continue baking for 10–15 minutes more, or until the internal temperature reaches 160°F.

Let rest 5 minutes before slicing. Serve with salad and roasted carrots.