Preheat your oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment paper, or give it a light greasing to prevent sticking.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until nicely combined. Set this aside.
In a large bowl, whisk the melted butter and sugar until smooth and creamy. Beat in the eggs one by one, then stir in the vanilla extract and buttermilk until everything is well blended.
Slowly add the dry flour mixture into the wet ingredients. Mix just until everything comes together – a few small lumps are perfectly fine! Be careful not to overmix, as this helps keep your bread wonderfully tender.
Gently fold in your colorful red and green sprinkles. Mix minimally to keep their vibrant colors from bleeding into the batter.
Pour the batter into your prepared loaf pan and smooth the top. If you like, sprinkle with a little coarse sugar or extra sprinkles for a delightful, sparkly finish. Bake for 45-55 minutes, or until a toothpick poked into the center comes out clean.
Let the bread cool in the pan for about 10-15 minutes. Then, carefully transfer it to a wire rack to cool completely before slicing. This ensures perfect, neat slices!