Heat a smoker to 250°F. Use a mild wood such as cherry or apple so the smoke complements the Italian seasoning and marinara. Lightly oil a grill-safe meatloaf pan or foil-lined tray with the olive oil.

In a large bowl, stir the breadcrumbs and milk together. Let them stand for a few minutes, until the breadcrumbs are moistened.

Add the egg, onion, garlic, Italian seasoning, salt, and pepper. Mix to combine, then add the venison and ground pork. Fold gently until the mixture just comes together.

Press half of the meat mixture into the prepared pan. Sprinkle ½ cup of the mozzarella over it, leaving a small border around the edges. Add the remaining meat mixture and gently seal the edges so the cheese is enclosed.

Place the pan in the smoker. Smoke until the center reaches 150°F, then spread ¼ cup of marinara over the top and sprinkle with the remaining ¼ cup mozzarella. Continue smoking until the center reaches 160°F.

Remove the meatloaf from the smoker and let it rest for 10 minutes before slicing. Serve with the remaining ¼ cup marinara spooned over the slices.