For the artichokes: Preheat the oven to 300 degrees F.
Cut the lemons in half and squeeze the juice into a large bowl of water. Reserve the squeezed lemon halves. Using a sharp knife, cut off the top two-thirds of the artichoke and remove the stem. Shave off the tough skin at the base. Remove the layers of tough leaves until you arrive at the inner, softer, light green ones. Then rub the cut end with a lemon half to keep it from browning. With a spoon, scoop out the choke (the fuzzy stuff) from the center to create a bowl. Place the artichoke into the lemon water to prevent it from discoloring while you finish preparing the remaining artichokes.
Place the hearts in a large roasting pan or baking dish. Add about 1/2-inch of the acidulated water. Cover with foil. Steam in the oven until the tender, 25 minutes; test doneness with the tip of your knife. Remove from the water and pat dry. Drizzle with olive oil.
Preheat the broiler.
Cook the artichokes until browned, 2 to 3 minutes. Set aside to cool. These will be the bowls for the stuffing.
For the stuffing: Return the oven to 300 degrees F. Heat the grapeseed oil in a medium skillet set over medium heat. Add the sausage and saute, breaking it up with a wooden spoon as it cooks, until browned and cooked through, about 10 minutes. Drain the excess grease from the skillet and stir in the parsley and sage. Cover and keep warm.
Spread the bagel pieces on a baking sheet and toast for 10 minutes. Remove to a large bowl and pour in the melted butter. Mix thoroughly to ensure the butter is absorbed.
Combine the tomatoes, cranberries, sugar, apples and onions in a medium saucepan and cook over low heat, stirring occasionally, until the ingredients soften and the flavors meld, about 10 minutes. Remove 16 of the cooked tomato halves and reserve for garnish.
Add the sausage and the tomato-apple mixture to the bagel cubes. Season with salt and white pepper. Toss gently to mix.
Dump the stuffing into the bowl of a food processor fitted with the blade attachment. Pulse until the stuffing breaks down but is not mushy, 3 to 4 times. Return the stuffing to the bowl. Stuff each artichoke with 1/3 cup of the stuffing. Garnish each with 2 reserved tomato halves and sprinkle with the spinach and pine nuts to serve.