Preheat the oven to 350 degrees F (180 degrees C).
Heat a 12-inch cast iron skillet over medium-high heat; cook breakfast sausage, stirring occasionally until browned, about 5 minutes. Drain excess grease.
Return sausage to skillet and add onion, bell pepper, jalapeno, and salt and continue cooking until peppers begin to soften, about 4 minutes. Remove from heat, drain any excess liquid, and set aside.
Add sour cream and 2 cups shredded cheese to a bowl; stir until well combined. Set aside.
Whisk baking mix, milk, and oil together in a separate bowl until smooth. Add crumbled bacon and mix well; set aside.
Sprinkle tomatoes evenly over sausage. Carefully spoon cheese mixture over tomatoes. Pour baking mix mixture on top and sprinkle with remaining cheese.
Bake uncovered in the preheated oven until golden brown, about 30 minutes.
Let skillet rest for 10 minutes before serving. Garnish with sour cream and cilantro or green onions.
