Heat a 12-inch cast iron skillet over medium-high heat. Add in the olive oil and butter. Once melted, add in the chicken and cook until no longer pink, about 7-10 minutes.
*You can use shredded chicken, canned chicken, rotisserie chicken, or any cooked chicken you have. Skip the second step and just add the cooked chicken in your mixture in step 3, then continue with the recipe.**I usually use 1 teaspoon of salt and pepper per pound.Tips:
I recommend using a cast iron skillet (or another oven-safe skillet), so you can make this casserole a one-pan recipe. Otherwise, warm up the filling on the stovetop, then transfer to a casserole dish, top with tater tots, and bake.
Make sure the chicken pieces are all about the same size (1-inch cubes) so they cook evenly and stay juicy.
When browning the chicken, work in batches if needed. Overcrowding steams the meat instead of searing it, which affects flavor and texture.
There's no need to thaw the frozen tater tots or veggies before using. Everything will warm up and cook through in the oven.
For extra-crispy tater tots, arrange them in a single layer on top (not overlapping too much). You can even bake the tots on a separate sheet for 10 minutes first, then add them to the casserole.
Finish with a sprinkle of green onions, parsley, or even crumbled cooked bacon for extra flavor and presentation.
Reheat leftovers in the oven at 350°F for 15-20 minutes to re-crisp the tater tots. The microwave works in a pinch, but the tots will soften.
Make-Ahead: You can assemble the casserole up to 24 hours in advance, cover tightly, and refrigerate. Add 5-10 minutes of bake time if baking straight from the fridge. You can also freeze the assembled, unbaked casserole. Wrap tightly in foil and freeze up to 3 months. Bake from frozen at 375°F for 45–55 minutes, or until hot in the center.Storage: Store chicken tater tot casserole in an airtight container in the refrigerator for 3 days, or freeze for 3 months.