In a large saucepan over medium-low heat, bring buttermilk and butter to a low simmer, until butter just begins to melt. Remove from heat, stir in the maple syrup, and set aside to cool.

In a large mixing bowl, whisk together 3 cups of the bread flour, the baking soda, yeast, and salt.

Once the buttermilk mixture is lukewarm, add to the bread flour mixture, and using an electric hand mixer with dough hooks, mix together until all flour is incorporated.

Gradually add 2 cups of flour, reserving the last half cup for kneading with your hands. Turn the dough onto a floured surface and knead with the remaining flour until no longer sticky.

Place dough in a well greased bowl and cover with plastic wrap. Let rise for 1-½ hours or until doubled in size.

Remove dough from bowl and divide in half. Shape into 2 equal sized loaves and place in prepared loaf pans. Cover loosely with a cotton towel and let loaves rise for 30-40 minutes, until bread has risen above the top of the loaf pan.

Preheat oven to 375 degrees F. Bake bread for 30-35 minutes, until golden brown and loaf sounds hollow when tapped.

Remove bread from oven and let cool on a wire rack for 10 minutes. Remove bread from loaf pans and cool completely. Store in airtight bag.