Chocolate Walnut Banana Bread

Preheat the oven to 180C/350F. Butter and flour a loaf pan. Whisk the first 4 ingredients in a medium bowl to blend. Combine the chocolate chips and walnuts in small bowl; add 1 tablespoon flour mixture and toss to coat. Beat the butter in a large bowl until fluffy. Gradually add the sugar, beating until well blended. Beat in the eggs, 1 at a time, and then the mashed bananas, lemon juice and vanilla extract. Beat in the flour mixture, just until combined. Spoon 1/3 of batter into the pan. Sprinkle with half the nut mixture. Spoon 1/3 of the batter over. Sprinkle with the remaining nut mixture then cover with remaining batter. Run a knife through the batter in a zigzag pattern. ;Bake the bread until a cocktail stick inserted into the centre comes out clean, about 1 hour 5 minutes. Turn out onto a rack and cool.