Set oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with oil or nonstick spray.
In a large skillet over medium heat, brown ground beef, breaking it up as it cooks. Add chopped onion and bell pepper; sauté until soft, about 5–7 minutes.
Stir in taco seasoning and drained diced tomatoes with green chilies. Cook for 3–5 minutes until well combined, then remove from heat.
Press refrigerated biscuit dough into the bottom of the greased dish to form an even layer. Bake for 5 minutes until slightly puffed.
Spread the cooked beef mixture evenly over the partially baked crust.
In a bowl, mix sour cream, mayonnaise, and ranch dressing mix until smooth. Gently spread over the beef layer.
Sprinkle cheddar and Monterey Jack cheese on top. Add sliced jalapeños if desired.
Bake for 25–30 minutes, until the cheese is melted and golden, and the biscuit base is fully cooked with crisp edges.