Heat the oven to 375°F. Lightly oil a small baking dish with the olive oil, using just enough to coat the base and sides.
Put the green peas in a bowl and lightly mash them with a fork, leaving some whole for texture. Add the chopped spinach, egg, breadcrumbs, onion, mint, Dijon mustard, salt, and black pepper. Stir to combine.
Add the ground turkey and mix gently with your hands or a fork until the ingredients are evenly distributed. Avoid overmixing, which can make the meatloaf dense.
Shape the mixture into a compact loaf in the prepared baking dish. Bake until the center reaches 165°F on an instant-read thermometer.
Let the meatloaf rest in the dish for 10 minutes, then slice and serve.