Heat the broiler. Place poblanos on a rimmed metal sheet 6 inches from the heat and broil for 8 to 10 minutes, turning until blistered. Cover in a bowl for 10 minutes, then peel and cut one lengthwise slit in each; gently remove seeds while keeping the peppers whole.
Lower the oven to 400°F. Heat 1 tablespoon oil in a skillet over medium-high heat and cook beef and onion for 8 minutes until beef reaches 160°F, breaking it into small crumbles. Drain excess fat.
Stir in garlic, cumin, ancho chile, salt and tomato paste for 1 minute. Add broth and hominy and simmer for 3 minutes until moist but not runny.
Remove from the heat and fold in half the Jack and lime juice. Divide filling evenly among the 6 poblanos and arrange slit-side up in a baking dish greased with the remaining teaspoon oil.
Scatter remaining Jack over the openings and bake for 12 to 15 minutes until the filling reaches 165°F and cheese melts. Rest for 5 minutes, then serve one filled pepper with 1 tablespoon crema per portion.