Arrange a rack in the middle of the oven and preheat according to the directions on the package of tater tots.
Line a large sheet pan with parchment paper. Spread out the tater tots as evenly as possible. Bake the tater tots 5-10 minutes longer than the instructions suggest. This will result in a crispier and drier tot which will hold up better beneath the toppings. While the tater tots are cooking, prepare the Ranch dressing, Buffalo chicken and other toppings.
First, in a small bowl, whisk together the 3/4 cup buttermilk, sour cream, 1/2 teaspoon Kosher salt and Ranch Seasoning. Set aside.
Then, in a large bowl, combine the shredded chicken, mayonnaise, 1/4 cup buttermilk and Buffalo spice. Stir with a spatula until the chicken is coated. Set aside.
Portion out and have the remaining toppings handy. Once the tater tots are golden brown and crisp, gather them together on the sheet pan into a neat pile and evenly sprinkle the Monterey Jack cheese and blue cheese crumbles on top.
Return the pan to the oven and broil on high for 3 minutes or until the cheese is melted. Once melted, evenly sprinkle the shredded chicken and broil for another 3 minutes or until the cheese has started to bubble and blister. The chicken will appear shiny and juicy when hot.
Right before serving, garnishing the totchos with tomatoes, scallions and jalapeños. Enjoy with a generous drizzle of ranch dressing and keep the remainder on the side for dunking.