1. Preheat your oven to 375°F (190°C). Lightly grease a large baking dish or rimmed baking sheet with non-stick spray or a bit of vegetable oil to prevent sticking.
2. In a large skillet over medium heat, sauté the chopped onion until translucent, about 3-4 minutes. Add the minced garlic and cook for another 30 seconds until fragrant.
3. Add the ground beef or turkey to the skillet. Break it apart with a wooden spoon and cook until browned and cooked through, about 6-8 minutes. Drain excess fat if needed.
4. Sprinkle the taco seasoning over the meat, pour in 1/2 cup of water, and stir to combine. Let the mixture simmer for 3-4 minutes until slightly thickened. Stir in the black beans and diced tomatoes with green chilies, then remove from heat.
5. Arrange the taco shells standing upright in the prepared baking dish, creating a snug fit but leaving some space to stand. Spoon the meat mixture evenly into each shell, filling them generously.
6. Sprinkle a mix of cheddar and Monterey Jack cheese over the filled tacos, making sure each one gets a good layer of melty goodness.
7. Bake in the preheated oven for 12-15 minutes, or until the cheese is bubbling and starting to brown slightly. You’ll notice the shells crisping up beautifully around the edges.
8. Remove from the oven and let the tacos cool for 2-3 minutes—this helps the cheese set just enough for easier handling. Garnish with chopped fresh cilantro if you like, then serve warm.

When I first made this recipe for Maya and Eli, I was pleasantly surprised at how the cheese melted perfectly without making the shells soggy—a balance I’d struggled with in earlier taco experiments. Baking them upright not only keeps the shells crisp but also makes assembling a breeze.