Preheat your oven to 375°F and lightly grease a 9x13 inch baking dish with a bit of the olive oil. While the oven heats, cut the corn tortillas into 1-inch strips and set aside. Dice the bell peppers into small, uniform pieces so they cook evenly in the casserole. Measure out the taco seasoning and have it ready near your cooking station. This prep work ensures you won't be scrambling mid-cooking and allows you to work efficiently through the remaining steps.

Heat a large skillet over medium-high heat and add the remaining olive oil. Once shimmering, add the ground turkey and cook for 8-10 minutes, breaking it apart as it cooks with a wooden spoon, until it's browned and cooked through. I like to let it get some golden color on the edges—this develops richer flavor. Once cooked, add the taco seasoning and taco sauce, stirring well to coat all the meat. Cook for 2-3 minutes more, allowing the flavors to meld together.

In a separate small saucepan, combine the refried beans with about 1/4 cup water over medium heat. Stir frequently for 3-4 minutes until the beans are warmed through and reach a smooth, spreadable consistency. The water helps loosen the beans so they layer evenly throughout the casserole without clumping. The creamy texture of quality refried beans (I use Rosarita) really makes a difference in the final dish's richness.

Spread a thin layer of the warmed refried beans from Step 3 across the bottom of the prepared baking dish. Arrange half of the tortilla strips over the beans in a single layer, overlapping slightly. Spread half of the cooked meat mixture from Step 2 over the tortillas, then sprinkle half of the diced bell peppers across the meat. Add another layer of half the remaining refried beans, and top with 1.75 cups of the shredded Mexican cheese. Repeat the exact same layers: tortilla strips, remaining meat mixture, remaining bell peppers, remaining beans, and finish with the final 1.75 cups of cheese on top. This even layering ensures every bite has all the components.

Place the casserole in the preheated 375°F oven and bake uncovered for 30-40 minutes, until the cheese on top is melted and slightly golden, and you can see the filling bubbling around the edges. Start checking around 30 minutes so you don't overbake. Remove from the oven and let cool for 5-10 minutes before serving—this resting time helps the layers set slightly so they don't fall apart when you cut and serve.

Once cooled slightly, top the warm casserole with your desired fresh toppings, adding them just before serving so they stay crisp. Layer on shredded lettuce, diced tomatoes, sliced black olives, diced red onion, sliced jalapeños, and fresh cilantro. Serve individual portions with a dollop of sour cream, fresh avocado slices, salsa on the side, and a handful of Fritos corn chips for that irresistible salty crunch. I like to let each person customize their own plate with toppings rather than loading everything on the casserole itself.