Place tater tots, bacon, sausage, cheddar cheese, and green onions in a lightly greased 9x13-inch baking dish.
In a medium bowl, whisk together eggs, half-and-half, sour cream and Ranch seasoning.
Pour egg mixture over tater tots. Bake covered for 25 minutes. Uncover and bake for 20 to 35 more minutes. It is done when the top is golden and crispy and the eggs are set.
No need to thaw the tater tots, but I do like to take them out of the freezer 20 to 30 minutes before assembling the casserole. If you are assembling it the night before, you can just add them in fully frozen.