Preheat your oven to 350°F (175°C) and prepare a 9x5-inch loaf pan by greasing or lining it with parchment paper.

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

In a large mixing bowl, combine melted butter and sugar until smooth. Add eggs one at a time, mixing well after each addition. Stir in vanilla and buttermilk until fully incorporated.

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

Fold in the sprinkles carefully until evenly distributed.

Pour the batter into the prepared loaf pan and smooth the top. Optionally, sprinkle coarse sugar or additional sprinkles on top.

Bake for 45-55 minutes, checking doneness with a toothpick that should come out clean.

Allow to cool in the pan for 10-15 minutes before transferring to wire rack to cool completely.