Preheat oven to 400*. Cook Chorizo sausage in a skillet over medium/high heat until cooked through. Drain off excess fat leaving only a little in the skillet.
Cook diced onions in skillet for 5 minutes, and then add in mushrooms, cook until tender. While these are cooking.
In a medium bowl, mix together the chorizo, Monterey jack cheese and cream cheese. Mix the cheese mixture back into the skillet with the mushrooms and onions, cook for 2 minutes. Remove from heat.
Stuff the pepper halves with a tablespoon of the mixture and lay in a sprayed baking pan. Repeat until all peppers are stuffed. Bake in preheated oven for 20 minutes and tops are lightly browned. Enjoy!