Method

1. Preheat oven to 350°F (180°C). Grease and flour 9×5 inch loaf pan or line with parchment paper.
2. In large bowl, beat butter until soft. Massage lemon zest into sugar and add to butter. Cream together until light and fluffy. Beat in bean puree, mix well. Beat in eggs, vanilla and lemon juice. 
3. In separate bowl, mix flour, baking powder, baking soda and salt.
4. Use 1/2 Tbsp of flour mix to toss with frozen blueberries.
5. 1. Add dry ingredients and milk to creamed butter and beans in three alternating parts, starting and ending with dry ingredients. Mix until just combined.
6. Gently fold in blueberries, do not over mix.
7. Pour batter into prepared loaf pan.
8. Bake for 60-65 minutes until golden and toothpick inserted into center comes out clean. Do not underbake.
9. Cool in pan on wire rack for 10 minutes before transferring to wire rack to cool completely before glazing.
10. To glaze, mix powdered sugar, milk and lemon juice until smooth. Drizzle over cooled loaf.