1. Heat oven to 350°F. Place about 40 foil baking cups (2-inches in diameter) in muffin cups. (Foil cups may also be placed directly on cookie sheets.)
2. Stir together cocoa and oil in large bowl until smooth; stir in sugar. Beat in eggs and vanilla; stir in flour, baking powder and salt. Stir in 1 cup peanut butter chips, reserving remaining 2/3 cup for frosting. Drop mixture by rounded tablespoonfuls into baking cups.
3. Bake 15 to 18 minutes or just until set and small cracks appear on surface. Remove from oven; immediately place about 6 reserved peanut butter chips on center of each brownie. Let stand several minutes to soften; swirl melted chips with knife or spatula. Garnish with pecan half, if desired. About 3 dozen brownies.