Combine butter, unsweetened chocolate, and 1 1/2 cups chocolate morsels in a large heavy saucepan.

Cook over low heat, stirring constantly, until butter and chocolate melt; cool.

Combine flour, baking powder, and salt; set aside.

Beat eggs, sugar, and vanilla at medium speed with an electric mixer.

Gradually add flour mixture to egg mixture, beating well.

Add chocolate mixture; beat well.

Stir in remaining 1 1/2 cups chocolate morsels and pecans.

Drop dough by 2 tablespoonfuls 1 inch apart onto parchment paper-lined baking sheets.

Bake at 350° for 10 minutes. Cool slightly on baking sheets; remove to wire racks to cool completely.