Set up a steamer basket over boiling water. Rub the artichokes with the cut lemons as you trim them. Steam the artichokes until theyre nice and tender and the leaves pull away easily, about 30 minutes. Cool the artichokes upside down so they can drain. Carefully pull out the center pieces and scrape out the choke (all the little fibers at the center), leaving the artichoke intact. Place the artichokes in a baking dish with 1/8 inch water, just enough to produce a little steam in the oven.
In a large skillet, warm up the 2/3 cup EVOO over medium heat. Melt the butter into the oil. Add the anchovies and stir until melted into the oil and butter. Add the garlic and red pepper flakes and stir that for a minute or two. Add the panko a little at a time until all of the butter-oil mixture has been absorbed evenly. Keep cooking to toast until deeply golden. Let cool, then stir in the parsley, Parm and black pepper to taste.
Fill all of the leaves, leaf by leaf, of each artichoke with the panko mixture until you get into the center. They should more than triple in width. Any leftover panko mixture can be piled onto the top of the artichokes to fill the center.
Position a rack in the middle of the oven and preheat to 400 degrees . Drizzle the artichokes with a little more EVOO, cover with foil and roast until hot, about 20 minutes. Uncover and roast until the edges of the leaves curl up and then become a bit pointy again. Serve at room temperature.