Preheat the oven to 400°F (200°C).

Combine tomatoes, garlic, serranos, onion, poblano, and olive oil in a large ovenproof skillet.

Season with salt and pepper.

Cook over moderately high heat until vegetables are sizzling and chiles begin to blister.

Transfer skillet to the oven and roast for 20 minutes, until tender and lightly browned.

Return skillet to the stove.

Stir in tomato paste and chipotle and cook over moderate heat until tomato paste caramelizes (about 2 minutes).

Add chicken stock and bring to a boil, scraping up any browned bits.

Remove from heat and let cool for 15 minutes.

Puree the contents of the skillet in a blender until smooth.

Wipe out the skillet.

Strain the sauce into the skillet.

Stir in sugar and lemon juice; season with salt and pepper.

Keep warm over moderate heat.

Heat olive oil in a large skillet until shimmering.

Add mushrooms, season with salt, and cook until softened and beginning to brown (about 7 minutes).

Stir in 1 cup of the enchilada sauce and the shredded chicken.

Wrap tortillas in a damp paper towel and microwave for 1 minute, or until soft and pliable.

Toss cheddar and Monterey Jack cheeses together.

Brush a 9x13 inch baking dish with vegetable oil.

Spoon 1/4 cup of chicken filling into each tortilla.

Top with 1/4 cup of cheese.

Roll up enchiladas and arrange in the baking dish.

Brush with remaining vegetable oil and pour remaining sauce on top, spreading evenly.

Sprinkle remaining cheese over the sauce.

Bake for 30 minutes, until sauce and cheese are bubbling and tortillas are browned and crisp.

Serve hot with Sour Cream Slaw, sour cream, and hot sauce.