Heat the oven to 375°F. Brush pepper halves with 1 teaspoon oil and bake cut-side up in a 9-by-13-inch baking dish for 15 minutes.
While the peppers bake, heat remaining oil in a skillet and brown beef for 7 to 8 minutes until it reaches 160°F. Drain excess fat, stir in garlic for 30 seconds and cool for 5 minutes.
Mix beef with squeezed spinach, ricotta, 1/2 cup crushed tomatoes, basil, oregano, 1/2 teaspoon salt and pepper. Divide among the softened pepper halves.
Mix remaining tomatoes and salt and pour around the peppers. Top the filling with mozzarella and bake for 20 to 25 minutes until the peppers are tender and the filling reaches 165°F.
Rest for 5 minutes, then spoon a little tomato sauce around each serving.