Brown meat and onions, drain. Stir in chili powder and garlic salt. Mix well. Add i cup of the enchilada sauce and simmer on medium low heat for about 5 minutes. While the meat is simmering, heat about 2 tablespoons oil in a small skillet and dip the corn shells to heat them turning once add more oil as needed. Place the warmed shells on a paper towel to absorb excess oil.
Spray pam in a 9 by 13 pan. Place about 2 T meat mixture and 2T of each cheese onto a shell, roll it and place a wooden toothpick to hold in place. You should have about 1/2 cup or so of meat left over. Add to that the rest of the enchilada sauce. If you need to add another small can of enchilada sauce to make sure you have enough to completely cover the shells. I like my pretty wet so usually use at least one extra can of enchilada sauce. Bake for 20 minutes. Remove from oven and cover with remaining cheese. Return to over for about 5 minutes or until cheese melts. Remove toothpicks before serving. Serve with sour cream and black olives.