Step 1: Brown the Beef - Start by heating a large skillet over medium heat, then add the ground beef. Break it apart with a spoon as it cooks, just like you would for taco night. You want it browned all the way through with no pink left. I always take an extra minute here because browned beef brings more flavor than beef that is just cooked. If there is extra grease in the pan, drain it off so the finished casserole stays rich but not oily.
Step 2: Season the Beef - Once the beef is cooked, stir in the salt, pepper, and taco seasoning. Give it a good mix so every little crumble gets coated. This is the base flavor of the casserole, so do not rush it. If the skillet looks a little dry, you can splash in a spoonful of broth to help the seasoning loosen up and cling to the beef. It should smell like taco night at this point, which is always a good sign.
Step 3: Mix the Creamy Chipotle Rice - In a large bowl, stir together the nacho cheese sauce, sour cream, chipotle sauce, uncooked rice, beef broth, and drained Rotel. Make sure the rice is mixed in evenly so it cooks properly in the slow cooker. This mixture may look a little loose right now, but that is exactly what you want. The rice needs that liquid to soften, and while it cooks, it turns the whole casserole creamy and thick.
Step 4: Grease the Slow Cooker and Start Layering - Lightly grease the inside of your slow cooker so serving and cleanup are easier later. Spoon a thin layer of the seasoned beef across the bottom. This first layer helps keep the tortillas from sticking directly to the cooker and gives every scoop a little beef from the start. Nothing fancy here, just spread it out the best you can.
Step 5: Add the Tortilla Layer - Lay flour tortillas over the beef, tearing them as needed to fit the shape of your slow cooker. I never worry about making this part pretty. Think of it like patching a little tortilla quilt. The tortillas soften as they cook and help give the casserole that burrito style texture.
Step 6: Build the Beef and Rice Layers - Spoon more seasoned beef over the tortillas, then add some of the creamy chipotle rice mixture. Spread it gently so the rice is not all piled in one spot. The goal is to get beef, rice, sauce, and tortillas spread throughout the casserole. That way, when you scoop it later, nobody gets a sad plain bite.
Step 7: Add Crunch and Cheese - Sprinkle on some crushed tortilla strips and some Mexican blend cheese. The cheese melts into the rice and beef, while the tortilla strips add a little texture. Some of the strips inside will soften, and that is okay. They still bring flavor and help build that layered burrito feeling.
Step 8: Repeat the Layers - Keep repeating the tortillas, beef, rice mixture, tortilla strips, and Mexican blend cheese until everything is used. Finish with cheese on top. I like to press the top down very gently with the back of a spoon, just enough to settle the layers together. Do not pack it tight though, because the rice still needs room to cook and absorb the liquid.
Step 9: Slow Cook Until Tender - Cover and cook on low for 4 to 5 hours or on high for 2 to 3 hours, until the rice is tender and the casserole is hot and bubbly. Slow cookers can vary a bit, so start checking near the early side of the cook time. You are looking for tender rice, melted cheese, and a casserole that holds together when scooped.
Step 10: Add the Cheddar Grilled Cheese Top - During the last 15 minutes of cooking, sprinkle the shredded cheddar cheese over the top. Cover again and let it melt until gooey. This is the part that gives the casserole that grilled cheese burrito feeling. The cheddar gets soft, rich, and beautiful, and it makes the whole top look like something you want to dive into with a big spoon.
Step 11: Finish and Serve - Right before serving, drizzle extra chipotle sauce over the top and sprinkle with extra tortilla strips. Let the casserole sit for 5 to 10 minutes before scooping. That little rest helps it thicken up, and it also keeps everyone from burning their mouth because cheesy slow cooker food comes out hotter than it looks. I speak from experience on that one.