Heat the oven to 400°F. Brush pepper halves with 1 teaspoon oil and bake cut-side up in a 9-by-13-inch dish for 15 minutes.
While the peppers bake, heat 1 teaspoon oil in a large skillet and cook cauliflower rice for 5 to 6 minutes until its moisture evaporates and the pieces are just tender. Transfer to a bowl.
Heat remaining oil in the skillet and brown beef and onion for 7 to 8 minutes until the meat reaches 160°F. Drain excess fat and stir in garlic for 30 seconds.
Add cream cheese, tomato paste, water, salt, paprika and pepper; stir over low heat until smooth. Fold in cauliflower rice and fill the softened pepper halves.
Top with Monterey Jack and bake for 15 to 18 minutes until the peppers are tender and the filling reaches 165°F. Rest for 5 minutes before serving.