Preheat the Oven: Preheat the oven to 400°F (200°C). Ensure the rack is positioned in the middle of the oven for even heating throughout the casserole.

Prepare Chicken Tenders: If using frozen chicken tenders, let them sit at room temperature for about 5 minutes to soften slightly for easier slicing. If you prefer smaller pieces throughout the casserole, slice them now; otherwise, you can leave them whole.

Layer Mashed Potatoes: Spread the mashed potatoes evenly across the bottom of a 9 x 13-inch casserole dish, creating a smooth, even base. For best results, warm the mashed potatoes beforehand if they've been refrigerated to ensure even heating in the oven.

Add Corn and Cheese: Layer the corn kernels evenly over the mashed potatoes, followed by an even distribution of the freshly grated cheddar cheese. The cheese will create a delicious melty layer between the potatoes and chicken.

Arrange Chicken: Slice the chicken tenders into pieces of your desired size and distribute them evenly across the top of the casserole dish. This ensures every serving gets a good portion of chicken.

Bake the Casserole: Bake the casserole uncovered for 20 minutes if using frozen chicken tenders, or for 15 minutes if using homemade chicken tenders. The cheese should be bubbling and the chicken should reach an internal temperature of 165°F (74°C).

Prepare Gravy: While the casserole bakes, heat the gravy on the stovetop according to the package instructions or your recipe. Stir occasionally to prevent scorching and ensure smooth consistency.

Finish and Serve: Remove the casserole from the oven, drizzle the prepared gravy over the top, and serve immediately while hot and bubbly for the best flavor and texture.