Lightly coat 6 mini loaf pans with non-stick spray and line with parchment paper.
Whisk flour, bicarb and salt in a medium bowl.
Using an electric mixer on medium-high speed beat brown sugar, mayonnaise and butter in a large bowl until light and fluffy, about 4 minutes. Add eggs one at a time, beating to blend after each addition and scraping down sides and bottom of bowl as needed.
Reduce speed to low, add flour mixture, and mix until just combined. Add bananas and mix just until combined. Fold in the pistachios. Spoon 2 tbsp of the batter into each prepared tin. Spoon 1 tsp jam into the centre of each and use a fork to gently swirl into the batter. Divide remaining batter between the tins, use a spatula to smooth the tops then repeat with jam on the top of each loaf.
Bake loaves for 45-50 mins or until a tester inserted into the centre comes out clean.
Transfer pan to a wire rack and let bread cool in pan 1 hour before turning out onto a wire rack to cool.
