Creating Watermelon Cupcakes can be a delightful experience if you follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a muffin tin with cupcake liners.

2. Mix Dry Ingredients: In a bowl, sift together the flour, sugar, baking soda, baking powder, and salt. Set aside.

3. Cream Butter and Sugar: In another large bowl, cream the softened butter until light and fluffy. Gradually add the granulated sugar and mix until combined.

4. Add Eggs and Vanilla: Beat in the eggs one at a time, followed by the vanilla extract. Mix until fully incorporated.

5. Combine Mixtures: Gradually mix the dry ingredients into the wet ingredients, alternating with the buttermilk. Start and end with the dry ingredients. Mix until just combined.

6. Add Watermelon Puree: Gently fold in the watermelon puree until the batter is smooth and combined.

7. Fill Cupcake Liners: Spoon the batter into the prepared cupcake liners, filling each about ⅔ of the way full.

8. Bake: Place in the oven and bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

9. Cool: Remove from the oven and let the cupcakes cool in the pan for about 15 minutes, then transfer to a wire rack to cool completely.

10. Make the Frosting: In a medium bowl, beat together the softened butter, powdered sugar, watermelon juice, and vanilla extract until creamy and smooth. Add a few drops of green food coloring if desired.

11. Frost the Cupcakes: Once the cupcakes are completely cool, frost them with the watermelon frosting using a piping bag for an elegant look.

12. Decorate: Optionally, decorate with mini chocolate chips or sprinkles for a fun touch to your Watermelon Cupcakes.