Preheat your oven to 375°F (190°C).
Drain the soaked beans and rinse them under cold water. Set aside.
In a large saucepan, heat the olive oil over medium heat. Add the diced onion and sauté until soft and translucent, about 5-7 minutes.
Add the minced garlic, diced carrots, and diced celery to the saucepan. Cook for another 5-7 minutes, or until the vegetables are tender.
Stir in the canned tomatoes, tomato paste, oregano, thyme, smoked paprika, salt, and pepper. Cook for a few more minutes until everything is well combined.
Add the drained Gigantes beans and vegetable broth to the saucepan. Stir everything together.
Transfer the mixture to a large baking dish, making sure that the beans are submerged in the liquid.
Cover the baking dish with aluminum foil and bake in the preheated oven for 1 1/2 to 2 hours, or until the beans are tender and the sauce is thick and bubbly.
Remove the foil from the baking dish and bake for an additional 15-20 minutes, or until the top is golden brown and crispy.
Serve hot and enjoy your delicious Greek Gigantes Plaki!