Season the chicken thighs on both sides with salt and pepper. Heat a small Dutch oven over medium high heat and add the olive oil. When hot, add the chicken and brown on both sides, 4 to 6 minutes. Add the onion, bell pepper, and garlic and stir until fragrant. Add the chicken stock, cumin, chili powder and oregano and bring to a boil. Cover the pot, reduce the heat to a simmer, and cook until the chicken is fork-tender, 35 to 45 minutes. Set aside to cool in the broth.

Once cool enough to handle, remove the chicken from the broth and shred it using two forks. Place in a small bowl and add enough of the broth remaining in the pot to keep the chicken moist. Season with salt and pepper if necessary, then cover and set aside.

*Note:  If you have 2 ½ to 3 cups of leftover roasted and shredded chicken, you can skip the steps above for cooking the chicken and proceed to the next step.

While the chicken is cooking, preheat the broiler and position a rack about 8 inches from the broiler unit.

Rub the poblanos on all sides with 1 tablespoon of the vegetable oil and place on a small baking sheet. Broil, turning once midway, until peppers are blistered on both sides and lightly charred in spots, 15 to 20 minutes. Remove from the oven and transfer to a paper bag, seal, and set aside to steam until peppers are cool enough to handle. Adjust the oven temperature to 350 degrees F and position a rack in the center of the oven.

Once the poblanos have cooled, rub the charred skins off and discard stems and seeds. Coarsely dice the peppers and set aside.

Heat a small nonstick skillet over medium-high heat until hot. Brush the tortillas lightly on both sides with the remaining vegetable oil. One by one, warm the tortillas briefly in the hot skillet until lightly golden in some spots and very pliable, 30 seconds to 1 minute per side. As tortillas are warmed, transfer them to a plate, set aside, and cover with a damp cloth so that they don't dry out.

In a small bowl, combine the crema and heavy cream and stir to combine.

To assemble the enchiladas:

Spoon about 1 cup of the Tomatillo Sauce over the bottom of a large baking dish.

Working one at a time, fill each tortilla with about ¼ cup of the shredded chicken, 2 tablespoons of the grated cheese, and some of the diced chiles. Roll the tortillas up tightly and place them seam side down in the baking dish, fitting them snugly next to one another as each one is filled and added to the dish. If you have any chicken or poblanos leftover, you can sprinkle them over the top of the enchiladas. Pour the remaining Tomatillo Sauce over the enchiladas and then spoon the crema mixture over the top. Sprinkle the remaining grated queso enchilada and the crumbled queso fresco on top.

Transfer to the oven and bake until the enchiladas are warmed through and the cheeses are melted, 20 to 30 minutes.

Serve hot, garnished with the chopped cilantro and salsa, if desired.