Makes 2 loaves
Preheat oven to 350 degrees.
Melt butter in a saucepan and continue to cook over medium low heat until brown bits form on bottom of pan. Remove from heat. Let cool slightly; then stir in sugar. Transfer to a large mixing bowl. Add eggs, bananas and vanilla and beat until well combined.
In a separate bowl, whisk together whole wheat pastry flour, bread flour, salt and baking soda. Gradually add to banana batter and mix until just combined.
Divide between two 8" loaf pans. Bake 50-55 minutes or until toothpick inserted in center comes out clean.
Adapted from The Professional Pastry Chef by Bo Friberg