Using a chef’s knife, trim a couple of inches off the top of each artichoke and cut enough off the base to create a stable, flat surface so the artichokes can stand upright without wobbling. Remove any especially tough outer leaves—these are usually small and near the bottom—and discard them. Then, use kitchen scissors to snip off the sharp tips of the remaining leaves. Drizzle about 1 tablespoon of the lemon juice over each artichoke.
Fill a steamer pot with a few inches of water and place a rack on top. Cover and bring the water to a boil, then reduce the heat to low to maintain a simmer. Stand the artichokes upright on the rack, stem-end up, cover, and steam until tender, about 45 minutes. You should be able to pull off one of the outer leaves with just a slight tug. Set the artichokes aside to cool.
While they are steaming, preheat the oven to 375°F and begin preparing the stuffing.
In a large sauté pan, melt the butter over medium-low heat. Let it simmer until it starts to brown, about 5 minutes. Add the shallots and garlic and cook until softened, about 3 minutes. Stir in the remaining ½ cup of lemon juice and the vegetable broth. Allow the mixture to simmer gently for about 4 minutes. Add the breadcrumbs and parsley, mix well, then remove from the heat. Season to taste with salt and pepper. Set aside to cool.
When the artichokes are cool enough to handle, gently pull the leaves away from the center just enough to see the choke. Use a spoon to carefully scrape away and discard all the fuzzy choke, revealing a clean artichoke heart.
Place the artichokes upright in a baking dish that holds them snugly. Using a spoon or your hands, generously fill the center of each artichoke with the stuffing—pack it in to the fullest! Also, fill the spaces between the leaves as much as possible. Sprinkle each artichoke with 1 tablespoon of Parmesan cheese, then drizzle with 1 tablespoon of olive oil.
Bake the stuffed artichokes in the preheated 375°F oven until the breadcrumbs are golden and the cheese has melted, about 15 minutes. Allow them to cool for a few minutes before serving. You may slice them into halves or quarters for sharing, or serve them whole for everyone to enjoy.