Preheat your oven to 375°F and lightly grease a 9x13 inch baking dish. While the oven heats, finely dice the onion into 1/4-inch pieces and seed and dice the poblano pepper into 1/2-inch pieces. Drain the canned green chiles, pat them dry with paper towels, and set aside—this removes excess moisture so the casserole won't be watery. Having everything prepped before you start cooking allows you to move through the recipe smoothly without interruptions.

Heat 5 teaspoons of olive oil in a large skillet over medium-high heat. Once the oil is hot, add the diced onion and poblano pepper, cooking for 4-5 minutes, stirring occasionally, until they become soft and the onion starts to brown at the edges—this develops deeper flavor in your filling. Add the ground turkey to the same skillet, breaking it apart as it cooks with a wooden spoon. Season with salt and black pepper, and cook until the turkey is no longer pink and begins to brown, about 8-10 minutes. I find that browning the turkey directly in the pan with the aromatics adds more flavor than cooking them separately.

Pour both cans of red enchilada sauce into the skillet with the browned turkey and vegetables, then add 1 teaspoon of chili powder and stir well to combine. Reduce the heat to low and let the mixture simmer for 30 minutes, stirring occasionally. This simmering time allows the flavors to meld and the sauce to reduce slightly, creating a rich, cohesive filling. Once done, remove from heat and let cool for 5-10 minutes—this prevents the sour cream from curdling when you stir it in. I always let the filling cool slightly before adding the sour cream; it makes a difference in the final texture.

Stir 1 cup of sour cream into the cooled meat mixture until fully incorporated. The sour cream adds richness and helps balance the spice and heat from the enchilada sauce and chili powder. Set the filling aside while you assemble the casserole.

Spread half of the dried green chiles in the bottom of your prepared 9x13 inch baking dish, slightly overlapping them. Top with half of the meat filling from Step 4, spreading it evenly with a spatula. Sprinkle half of the mozzarella cheese (about 1.25 cups) over the meat layer. Repeat with the remaining green chiles as the second layer, followed by the remaining meat filling, and finish with a top layer combining the remaining mozzarella cheese and the Mexican blend cheese (1.25 cups mozzarella mixed with 3/4 cup Mexican blend). This layering creates an even distribution of flavor and texture throughout the casserole.

Place the assembled casserole in the preheated 375°F oven and bake for 30-35 minutes, until the cheese on top is melted and bubbly and the edges are slightly golden. If the top isn't browning enough toward the end of cooking, you can increase the heat to 425°F for the last 2-3 minutes. Remove from the oven and let rest for 5 minutes before serving—this allows the casserole to set slightly and makes portioning easier. Serve hot directly from the baking dish or spoon portions onto plates.