Preheat your oven to 350°F (175°C) and prepare a 9×5-inch loaf pan by greasing it with butter or oil and dusting it lightly with flour.

In a medium mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and cinnamon. Sift to eliminate lumps.

In a large mixing bowl, cream ½ cup softened butter and 1 cup granulated sugar together until light and fluffy. Add the eggs one at a time, followed by the vanilla extract.

Pour in ½ cup of buttermilk and stir until everything is nicely blended.

Gradually add the dry mixture into the wet ingredients, gently folding them together. Mix just until no flour is visible.

Fold in 1 to 2 cups of chopped rhubarb and any nuts or raisins if desired.

Pour the batter into your prepared loaf pan and smooth the top. Optionally sprinkle with sugar for topping.

Bake for 55-65 minutes or until a toothpick inserted in the center comes out clean or with moist crumbs.

Allow the bread to cool in the pan for about 10 minutes and then transfer it to a wire rack to cool completely.