In a bowl, make the spice mix for your chicken: blend the oregano, cumin, garlic powder, chili powder, salt and pepper.
Coat the chicken on both sides with the spice mix, pressing it in well; set aside.
In a medium skillet, melt the oil and butter. Add the chicken and cook about 8-10 minutes or until the chicken is done; turning once during cooking.
Set aside and allow the chicken to cool slightly while you make the sauce.
To the oil and butter in the skillet, add the tomato sauce, garlic powder, hot sauce and extra salt and pepper.
Simmer until just reduced and a little thicker; about 5-7 minutes or so, then turn off the heat.
Using two forks or your hands, shred the chicken as finely as you like it.
Add the chicken to the sauce and stir to coat.
On a baking sheet, pile up half the tortilla chips and top with half the chicken. Repeat with the other half of the chips and chicken then top with shredded cheddar.
Broil until the cheese melts and it hot and bubbly--about 5 minutes or so.
Remove from the oven and add the toppings of your choice.