Prep. Pre-heat oven to 350 °F and line muffin tin with 12 cupcake liners.
Mix the dry ingredients. In a large bowl mix together the flour, sugar, baking soda and salt with a whisk
Mix the wet ingredients. In a separate large bowl mix together the sour cream, eggs, melted butter and calamansi juice with a whisk until nice and smooth and creamy.
Add the dry into the wet. Take the bowl of dry ingredients and pour it into the bowl of mixed wet ingredients. Fold in the dry ingredients with a spatula slowly until the dry ingredients are fully incorporated.
Fill Muffin Tin. Scoop the Calamansi Muffin batter into each of the lined muffin cups. Then top each with a teaspoon of cereal polvoron.
Bake for 20 minutes. Take out of the oven and leave to cool fully.