Make the Cupcakes:

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 large bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt.
3. Mix Wet Ingredients: In another bowl, whisk together the granulated sugar, brown sugar, eggs, buttermilk, vegetable oil, and vanilla extract until smooth.
4. Combine: Gradually add the dry ingredients to the wet mixture, mixing until just combined. Carefully stir in the boiling water until smooth (the batter will be thin).
5. Bake: Pour the batter into the prepared cupcake liners, filling each about 2/3 full. Bake for 18-20 minutes, or until a toothpick inserted in the center comes out clean. Let cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Make the Raspberry Sauce:

6. Cook the Raspberries: In a small saucepan over medium heat, combine the raspberries, sugar, and lemon juice. Cook until the raspberries break down and the mixture becomes syrupy, about 5-7 minutes. If you prefer a thicker sauce, dissolve cornstarch in a tablespoon of water and add it to the saucepan, stirring until thickened.
7. Cool: Remove from heat and let the sauce cool. It will thicken further as it cools.

Make the Frosting:

8. Beat the Butter: In a large bowl, beat the softened butter until creamy.
9. Add Sugar and Cream: Gradually add the powdered sugar, mixing on low until combined. Add the heavy cream and vanilla extract, then beat on high until fluffy. If desired, mix in a few drops of red food coloring for a spooky effect.

Assemble the Cupcakes:

10. Frost the Cupcakes: Once the cupcakes are completely cool, frost them generously with the buttercream frosting using a piping bag or a spatula.
11. Drizzle Raspberry Sauce: Drizzle the cooled raspberry sauce over the frosted cupcakes to create a “bloody” effect. You can let it drip down the sides for a more dramatic look.