Put the ground deer burger and water in a large skillet over medium-high heat. Mix the water into the burger well and continue to stir and break up the meat as it fries. You want the meat mixture to turn out nice and smooth.
Once the ground deer burger is halfway done, add the spices, oregano, basil, and celery, and continue frying until the meat is done.
Add the spaghetti sauce and let it simmer for another minute and then remove it from the heat.
Prepare tortellini according the package directions.
Preheat the oven to 375 F °.
When the tortellini is done, drain the water and gently spoon half of it evenly into a 9″ x 13″ casserole dish.
Top it with the ground deer burger and sauce mixture, then another layer of tortellini, then a final layer of the meat mixture.
Add mozzarella cheese on top and let it bake for about 5 minutes–just until the cheese is melted and gooey.