Preheat oven to 350 degrees. Spray bottom of a 9x13 or similar sized baking dish with cooking spray.
In a large skillet over medium-high heat, saute sausage until cooked through. Remove and set aside, leaving grease from pork in bottom of skillet.
Add diced onion to the skillet and saute until softened, about 6 minutes. Add garlic and saute for another minute. Remove from heat.
In a large bowl, stir together cooked sausage, thawed hash browns, cooked onion and garlic, sun dried tomatoes, and grated fresh Asiago PDO cheese.
In a medium sized bowl, whisk together eggs, milk, pepper, and seasoned salt. Once well combined pour over hash brown mixture and stir until well mixed.
Pour mixture into prepared baking dish. Cover with aluminum foil and bake for 40 minutes.
Remove foil, sprinkle grated aged Asiago PDO cheese over top of casserole and bake for another 15 minutes, or until cheese is melted and top is lightly browned.