Pre-heat oven to 425° F
In a blender puree the tomatoes and their juices with the jalapeños, half the onions, and the crushed garlic until smooth. Season with salt to taste. Pour sauce into the 9×13 pan and spread evenly.
In the large mixing bowl, mix together the beans, cornmeal, 1 cup pepper jack cheese, the rest of the onions, minced garlic, cumin as well as the water, season with salt and pepper to taste.
Take each poblano half and stuff with bean mixture, making sure you have enough for all 8 pieces. Place stuffed poblanos in 9×13 pan on top of the sauce. Sprinkle poblanos with the remaning cheeses, making sure to cover completely. Cover pan with Aluminum foil, tightly, but making sure it doesn't touch the cheese top.
Place on middle oven rack for 45-55 minutes until poblanos are tender. Uncover and cook for another 10-15 minutes until cheese browned and sauce thickens. Remove from oven and let cool for 10-15 minutes.