Make the Cupcakes
Preheat the oven to 180°C / 350°F and line a muffin tin with cupcake liners.
In a large bowl, whisk together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Add eggs, oil, milk, and vanilla extract. Mix until smooth.
Slowly pour in the hot water (or coffee) and mix until the batter is thin and well combined.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Bake for 16–18 minutes, or until a toothpick inserted comes out clean.
Remove from oven and let cupcakes cool completely on a wire rack.
Make the Raspberry Frosting
Beat the softened butter until creamy and pale.
Gradually add powdered sugar, mixing on low speed.
Pour in the raspberry puree, vanilla extract, and salt.
Beat on medium-high speed for 2–3 minutes until fluffy.
Frost cooled cupcakes using a piping bag or spatula.