Preheat your oven to 375°F (190°C). Spray a 9x13-inch baking dish with cooking spray.(Olivia always helps me with this part, she loves saying, “Mom, I’m in charge of the oven!” even though I do the actual preheating.)
In a large skillet over medium heat, brown 2 pounds of ground beef with diced onions and bell pepper for about 8–10 minutes until tender. Add garlic and cook for 1 minute more.(This is when our kitchen smells like Taco Tuesday magic. Olivia usually comes running to stir and ask if it’s “taste test time.”)
Stir in the taco seasoning, black beans, salsa, and water. Simmer for 5 minutes, until thickened.(A quick mom tip: simmering brings out those deep, cozy flavors, don’t skip it!)
Spread a thin layer of the meat mixture on the bottom of the dish. Layer flour tortillas, then meat, then sour cream, and top with cheddar and pepper Jack cheese. Repeat until all ingredients are used, ending with cheese on top.(This is Olivia’s favorite part, she calls it “food stacking.” It’s messy, but we make memories with every tortilla.)
Cover with aluminum foil and bake for 30 minutes. Remove foil and bake another 10–15 minutes until the top is golden and bubbly.(We always peek through the oven window together, it’s like watching a gooey, cheesy volcano.)
Let it rest for 10 minutes before slicing to help the layers set. Garnish with sour cream, chopped tomatoes, cilantro, and jalapeños.(This is the hardest part for Olivia, waiting! But it’s worth it for those perfect layers.)