Preheat oven to 400 degrees. Heat olive oil in 10-inch skillet over medium heat. Put onions into skillet and sweat the onions until softened. Add garlic and cook for 30 seconds.
Bring a stockpot of water to a boil. Add carrots to the water and boil them for 8 minutes. Drain and set aside.
In a large bowl, combine ground venison, beef, bread crumbs, softened onions, garlic, Parmesan-Reggiano, Dijon mustard, eggs, salt, and pepper.
Form the meat mixture into a 1/2-inch thick, 10x16-inch rectangle on a Silpat or piece of wax paper. Lay the spinach leaves over the meat, leaving a 1/2-inch border around the perimeter of the rectangle. Layer Mozzarella slices on top of basil leaves and then lay the carrots lengthwise on top of the Mozzarella. Roll the meat lengthwise (starting with long side), making it as tight as possible. Pick up Silpat or wax paper and roll the loaf onto a rack that is placed on top of a half-sheet pan with sides.
Slice bacon in half and place width-wise over the loaf. Bake for 1 hour or until loaf reaches 165 degrees.
Transfer the meatloaf to a cutting board. Cut meatloaf into 1-inch slices and serve with salad, crusty bread, and your choice of side.