1. Preheat oven to 375 degrees. Coat a 9 x 13 inch pan with cooking spray. 2. Place the potato tots in a single layer on the bottom of the pan. 3. In a large bowl, whisk together the eggs and milk until thoroughly combined. 4. Stir in 3/4 of the bacon and 1 cup of the cheese. 5. Add salt and pepper to taste. 6. Pour the egg mixture over the potato tots. 7. Sprinkle the remaining bacon and cheese over the top of the egg mixture. 8. Bake for 45 minutes or until center is set. 9. Place the tomatoes, avocado, and chives in a bowl; stir to combine. Season with salt to taste. 10. Spoon the tomato mixture over the top of the casserole and serve.