Heat oven to 375°F. Lightly grease a 9x13-inch baking dish.
Press the biscuit pieces into the dish to form an even crust. Par-bake 8–10 minutes; set aside.
Warm the olive oil in a large skillet over medium-high heat.
Cook ground beef with onion and bell pepper, breaking up meat, until browned and softened, 6–8 minutes. Drain excess fat.
Stir in garlic, taco seasoning, and water. Simmer until thickened and saucy, 2–3 minutes. Season with salt, pepper, and paprika.
Spread the beef mixture over the baked crust. Scatter tomatoes and jalapeños evenly on top.
Combine sour cream, mayonnaise, and half the cheddar. Dollop and gently spread over the casserole.
Top with remaining cheese. Bake 18–22 minutes until bubbly and golden. Rest 10 minutes, garnish with green onions, and serve.