Heat a large oven-safe skillet over medium heat; add ground beef and cook, breaking up meat with a spatula, until fully browned, about 10 minutes. Drain any excess fat.
Stir in beef bone broth, milk, salsa, and taco seasoning. Mix well and bring to a gentle simmer.
Add pasta and stir to combine. Cover and simmer until pasta is tender, 8 to 12 minutes (or according to pasta package instructions), stirring occasionally. Adjust liquid as needed: if too thick, add a splash of milk; if too thin, simmer uncovered 1 to 2 minutes longer.
Reduce heat to low and stir in 3/4 of Cheddar cheese until melted and creamy. Sprinkle remaining cheese evenly on top.
Turn on the oven’s broiler and place a rack about 6 inches from the heat.
Place the skillet under the broiler until cheese is melted and lightly browned, 2 to 3 minutes.
Carefully remove skillet from the oven. For each serving, add a dollop of sour cream and sprinkle with fresh cilantro. Serve hot.
