Preheat the oven to 350°F (175°C) and prepare a 9x5-inch loaf pan.

In a medium mixing bowl, whisk together the flour, baking powder, baking soda, and salt.

In a large mixing bowl, melt the butter and whisk in the sugar until smooth. Add eggs one at a time, mixing well after each. Stir in vanilla and buttermilk.

Gradually add dry ingredients to wet mixture, stirring gently until just combined.

Gently fold in the sprinkles to the batter.

Pour the batter into the prepared pan and sprinkle the top with coarse sugar if desired.

Bake for 45–55 minutes until a toothpick comes out clean.

Let cool in the pan for 10–15 minutes before transferring to a wire rack.