Heat the oven to 400°F. Line a rimmed baking sheet with parchment paper.
In a large mixing bowl, combine the ground turkey, egg, breadcrumbs, Parmesan, onion, milk, salt, pepper, and 2 tablespoons of the pesto. Mix gently until just combined. Avoid overmixing, which can make the loaf dense.
Shape the mixture into a loaf about 8 inches long and place it in the center of the prepared baking sheet. Spread the remaining pesto over the top and sides.
Toss the cherry tomatoes with the olive oil. Arrange them around the meatloaf in a single layer.
Bake until the meatloaf is cooked through and reaches 165°F in the center, about 40 to 45 minutes. The tomatoes should be softened and lightly blistered. Rest the meatloaf for 5 minutes before slicing, then serve with the roasted tomatoes and their pan juices.