Trim the bottoms and tops of the artichokes and bring a pot of salted water to a boil. Place the artichokes in the water and reduce the heat to a simmer. Cover and cook for 30 minutes.
While the artichokes cook, make the filling and breadcrumb topping. In a medium bowl, mix spinach, artichokes, sour cream, mayonnaise, garlic, scallions, cayenne, salt and pepper. Set aside.
In a small bowl, mix breadcrumbs, Parmesan, salt and olive oil. Set aside.
Drain the artichokes and pat dry with a clean towel. Place on a baking sheet. Press the leaves gently back to reveal the inner choke and prickly leaves. Pull out the prickly leaves and gently scrape out the choke with a spoon.
Fill artichokes with spinach mixture. Sauce should cover tops and fill into artichoke leaves. Sprinkle breadcrumb mixture over tops of artichokes.
Bake the artichokes for 10-15 minutes or until the breadcrumbs are golden. Serve warm.