1. Beat eggs in a large bowl and set aside.
2. Combine flour, baking powder, and salt in a small bowl; stir into eggs, mixing well.
3. Add cheeses, butter, green onions and chiles; pour into greased 13 x 9 baking pan.
4. Bake at 350 until a knife tip inserted in center tests clean, 35 to 40 minutes.
5. Let stand 5 minutes and cut into squares.
6. Garnish as desired with sour cream and salsa.