Preheat oven to 475˚F.
Grease the bottom of a 9x13 baking dish with 1 tablespoon olive oil and set aside.
Working with 1 artichoke at a time, trim the stem to about 1-inch and cut 1-inch off the tip of the artichoke.
Break off the bottom 3 rows of tough outer leaves, and remove any dark green parts on the artichoke.
Cut the artichoke in half, lengthwise, then remove the fuzzy chokes in the center. Set aside.
Fill a large container or a baking dish with 8 cups water.
Cut 1 lemon in half; squeeze the lemon juice into the water.
Put the artichokes in the lemon water and keep in there for about 3 to 5 minutes.
Remove artichokes from the lemon water and shake off any excess liquid.
Transfer the artichokes to a large bowl and toss them with 2 tablespoons olive oil, ¾ teaspoon salt, and ¼ teaspoon black pepper.
Arrange artichokes, cut side down, on the bottom of previously prepared baking dish.
Cut the remaining 2 lemons in half and place them cut-side-up next to the artichokes.
Cover with aluminum foil and roast for about 25 to 30 minutes, or until artichoke leaves are browned and tender when poked with a knife.
Remove from oven and transfer the artichokes to a serving plate.
Grab the cooked lemons and squeeze out as much juice as possible into a mixing bowl.
To the lemon juice, whisk in the remaining olive oil, minced garlic, mustard, and parsley. Season with salt and pepper.
Drizzle the lemon dressing over the artichokes.
Garnish the artichokes with parsley and serve.