Heat oven to 350°F. Spread pecans in ungreased shallow pan. Bake uncovered 6 to 10 minutes, stirring occasionally, until light brown. Set aside.
In 3-quart heavy saucepan, cook butter, baking chocolate and 1 1/2 cups of the chocolate chips over low heat, stirring constantly, until butter and chocolate are melted. Remove from heat; cool.
In medium bowl, mix flour, baking powder and salt; set aside. In large bowl, beat eggs, sugar and vanilla with electric mixer on medium speed until well blended. On low speed, gradually beat in flour mixture. Add chocolate mixture; beat well. Stir in toasted pecans and remaining 1 1/2 cups chocolate chips.
Line cookie sheets with cooking parchment paper. Onto cookie sheets, drop dough by 2 tablespoonfuls 1 inch apart. Bake 10 minutes. Cool 2 minutes; remove from cookie sheets to cooling racks.