Preheat the oven to 350°F.

Cut the zucchini lengthwise, and scoop the insides out with a spoon.

Chop the inside parts, and add them to a medium bowl with the ground beef.

In a large skillet over medium-high heat, heat the olive oil.

Sauté the onion and garlic until the onion is slightly translucent, about 5 minutes.

Add the ground beef–zucchini mixture, and cook for about 5 minutes more, until completely browned, breaking the meat up as you cook it.

Season with salt and pepper.

Remove the skillet from the heat, and add the olives and hardboiled eggs.

Stir well.

Stuff the zucchini boats with the meat mixture, and place them on a baking sheet.

Bake for 45 minutes, until tender, and serve.