01 - Preheat oven to 425°F. Arrange tater tots in a single layer on a large baking sheet. Bake according to package directions, usually 25 to 30 minutes, flipping halfway through for even crispness.
02 - Heat olive oil in a large skillet over medium heat. Add diced onion and cook until softened, about 4 minutes. Stir in minced garlic and cook for 1 minute. Add ground beef and cook until browned, breaking up with a spoon, then drain excess fat.
03 - Add diced tomatoes, kidney beans, tomato paste, chili powder, cumin, smoked paprika, salt, and pepper to the beef. Simmer 10 to 12 minutes, stirring occasionally, until chili thickens. Adjust seasoning as needed.
04 - Cook elbow macaroni in a large pot of boiling salted water according to package instructions. Drain and set aside.
05 - Melt butter in a saucepan over medium heat. Add flour and cook for 1 minute, whisking constantly. Gradually pour in milk while whisking until smooth. Bring to a gentle simmer and cook until thickened, about 3 to 4 minutes. Remove from heat and stir in cheddar cheese until fully melted. Season with salt and pepper.
06 - Fold drained macaroni into the cheese sauce and mix evenly.
07 - Transfer baked tater tots to a large serving platter or ovenproof dish. Evenly spoon mac and cheese over the tots, then top with a generous layer of chili.
08 - Sprinkle Monterey Jack or additional cheddar cheese over assembled dish. Return to oven for 5 to 7 minutes, until cheese is melted and bubbly.
09 - Finish with sliced green onions, fresh cilantro, and jalapeño if desired. Serve immediately.