Preheat oven to 350° F.
Slice onion in half and peel away skin. Pull the onion apart, careful not to tear the layers from each half of the onion. When you have four complete circles, set layers aside.
Chop inside core of onion (layer not peeled).
Slice mozzarella cheese into four 1-ounce pieces. If block is 8 ounces, each cube should be 1/8th of entire block.
Combine venison, chopped onions, parsley, soy sauce, Worcestershire sauce, panko, brown sugar, and ketchup in mixing bowl.
Form venison mixture into four even-sized balls.
Make a well inside the balls and place one block of mozzarella cheese per meatball.
Place two layers of onion around outside of the venison mixture balls, one at a time, so that a complete circle is formed around the meat.
Wrap onion in bacon and secure with toothpicks on either side.
Bake onion bomb for 20 minutes.
Remove from oven, brush generously with favorite BBQ sauce.
Bake again for 10-15 minutes, or until bacon's desired crispness is reached.
Let cool for 5 minutes.
