Preheat the Blackstone griddle to medium-high heat and lightly oil the surface. Add the tomatillos, jalapeños, serrano peppers, and onion. Roast, turning occasionally, until softened and lightly charred, about 10–15 minutes. Remove from the griddle.
Add the roasted vegetables to a blender along with the raw garlic cloves, cilantro, and chicken bouillon. Blend until smooth. Taste and adjust seasoning if needed. Set aside.
Lower the griddle heat to medium. Drizzle with oil and add the chicken thighs. Season both sides with Chef Merito Chicken Seasoning, garlic powder, and Blackstone Street Taco Seasoning. Cook until fully cooked and nicely browned, about 5–6 minutes per side.
Remove the chicken from the griddle and let it rest for a few minutes, then chop into small, bite-size pieces. Set aside.
Lightly oil the griddle and warm the tortillas just until soft and flexible, about 10 seconds per side.
Dip each warm tortilla into the salsa verde, coating both sides. Add chopped chicken down the center, roll tightly, and place seam-side down on the griddle over low heat.
Once all enchiladas are on the griddle, pour the remaining salsa verde evenly over the top and sprinkle with shredded cheese.
Cover with a basting dome, keep heat on low, and cook until the cheese is fully melted and everything is warmed through, about 8–10 minutes.
Remove from the griddle and finish with sour cream and fresh chopped cilantro. Serve immediately.