Preheat oven to 375°F. Line twelve 1/2-cup muffin cups with paper liners. Stir 1/4 cup hot water and espresso powder in medium bowl until espresso powder dissolves. Add buttermilk, oil, eggs and vanilla and whisk until well blended. Mix flour, sugar, brown sugar, cocoa, baking powder, baking soda and salt in large bowl. Add buttermilk mixture and stir just until combined. Mix in chocolate chips and pecans. Divide batter equally among prepared muffin cups. Bake until tester inserted into center of muffins comes out clean, about 25 minutes. Transfer muffins to rack and cool.