Preheat the Oven: Preheat your oven to 180°C (350°F). Line a muffin tin with cupcake liners.

Cream the Butter and Condensed Milk: In a large bowl, cream together the softened butter and condensed milk using an electric mixer until light and fluffy. This will take a few minutes.

Beat in the Eggs: One at a time, beat in the eggs until well combined. Scrape down the sides of the bowl as needed.

Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt.

Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix, as this can lead to tough cupcakes.

Add Raisins (optional): If you're using raisins, fold them gently into the batter using a spatula.

Fill the Cupcake Liners: Divide the batter evenly between the prepared cupcake liners. Fill them about ¾ full.

Bake: Bake the cupcakes for 40-45 minutes, or until a toothpick inserted into the center comes out clean.

Cool and Decorate (optional): Let the cupcakes cool completely on a wire rack before decorating. You can drizzle them with melted chocolate, dust them with powdered sugar, or add your favorite frosting.