Prepare your bread bowls, if necessary, according to package instructions. Set aside.
Prepare chicken. Rub chicken with taco seasoning until fully covered. May need more or less depending on texture of seasoning and size of thighs. Cook chicken thighs in a non-stick pan over medium heat for 5-7 minutes on each side or until internal temperature reaches 165 degrees F.
In a non-stick pan, saute diced poblano and onion in a bit of butter until softened. Set aside.
While chicken is cooking, prepare your cheese sauce. First, make a roux by adding butter to a medium sized saucepan. Stir in the flour and cook, stirring constantly until the paste is cooked and bubbles a little bit but careful not to let it brown, about 2 minutes. Add in the warm milk, continuously stirring until the sauce thickens. Bring to a boil, adding salt and pepper to taste, then lower to low-medium heat and add in shredded cheddar cheese, stirring until totally combined and desired consistency.
Chop warm seasoned chicken and add to cheese sauce, stir to combine. Add diced poblano and onion and stir to combine.
Ladle cheesy chicken mixture into bread bowls and top with pickled jalapenos, if desired!