Preheat your oven to 350°F. Take a 9x13-inch casserole dish and spread ¼ cup of the enchilada sauce evenly across the bottom, covering the entire surface. Set aside.

Pour 1 teaspoon of olive oil into a large skillet and place over medium-high heat for about 1 minute until shimmering. Checkpoint: Oil should shimmer but not smoke.

Add 1 pound of ground beef and 1 diced white onion to the hot skillet. Using a wooden spoon or spatula, break up the beef into small, bite-sized pieces as it cooks. Continue cooking for 5-7 minutes, stirring occasionally, until the beef is completely browned (no pink remains) and the onion is translucent and soft. Drain excess grease if there is more than ¼ inch of fat pooling in the pan.

Add 2 minced garlic cloves to the cooked beef and onion mixture. Stir constantly for exactly 30 seconds—you'll know it's ready when the garlic becomes very fragrant and starts to lightly brown.

Sprinkle 1 (1 ounce) packet of taco seasoning over the beef mixture and stir to coat evenly. Add 1 cup frozen corn, 1 cup drained black beans, and ¾ cup water. Stir everything together until well combined.

Reduce the heat to medium and let the mixture simmer for 5-8 minutes, stirring occasionally, until most of the water has been absorbed and the mixture has thickened to a chili-like consistency. The sauce should coat a spoon without running off.

Remove the skillet from heat and stir in 1 cup of the shredded Mexican blend cheese until completely melted and incorporated. Set the beef mixture aside while you prepare the casserole.

Pour the entire meat mixture into the prepared 9x13-inch casserole dish, using a spatula to spread it evenly to all four corners and edges, creating an even layer about ½ inch thick.

Take 1 (16 ounce) bag of frozen tater tots directly from the freezer and arrange them in a single, tight layer over the meat mixture, covering as much surface area as possible. Don't thaw them—use them straight from frozen.

Drizzle the remaining enchilada sauce (approximately ¾ cup) evenly over the tater tot layer, using the back of a spoon to gently spread it so the tots are lightly coated. Then sprinkle the remaining 1 cup of shredded Mexican blend cheese over the top, covering all visible tater tots. Checkpoint: Everything should be evenly coated and the dish should look full and appetizing.

Place the casserole dish on the center rack of your preheated 350°F oven and bake for 25-30 minutes. The casserole is done when the filling below is visibly bubbly around the edges, the tater tots are golden brown and crispy on top, and the cheese is melted and slightly browned in spots.

Remove from the oven using oven mitts and let rest for 3-5 minutes before serving. This allows the casserole to set slightly and makes serving easier.

Troubleshooting Guide:If tater tots aren't crispy: Increase oven temperature to 375°F in the final 5-10 minutes, or broil for 2-3 minutes at the end (watch carefully to avoid burning cheese).

If filling is still watery: Simmer the beef mixture longer in step 6, aiming for a very thick consistency before adding to the dish.

If cheese is burning but filling isn't bubbly: Cover the top loosely with foil and continue baking until filling bubbles at the edges, then remove foil for final 2-3 minutes.

If casserole seems dry: Pour an extra ¼ cup enchilada sauce over the top before baking, or reduce initial baking time.

If some tater tots remain pale: Use a spatula to redistribute them or rotate the dish halfway through baking for even browning.