Preheat oven to 400 degrees. Coat a 9x9 baking dish (or similar size) with cooking spray. Set aside.
Combine Parmesan cheese, mayonnaise, chopped onion, lump crab meat, chopped artichokes, parsley, fine sea salt, white pepper and smoked paprika in a medium bowl. Toss to combine being carful to not break apart crab pieces.
Transfer mixture to prepared baking dish. Bake for 25 minutes, or until starting to lightly brown.
Place sourdough bread slices on a rimmed baking sheet. Place under high broil about 4 inches from the heating mechanism for 3-4 minutes or until they brown lightly. Remove.
Evenly spoon hot crab mixture over each slice of bread, 2 slices of tomato and 2 slices of Monterey Jack cheese.
Place back under the broiler until cheese melts, approximately 2 minutes, but watch closely considering that broilers vary greatly.
Serve open face and hot.
If you've tried this recipe, please come back and let us know how it was!
*Freshly grated is highly preferred for this recipe. You may not get the same results with pre-shredded cheese. **Use blue crab meat. You can also use backfin or claw meat.