Preheat the oven to 350°F (175°C) and line a standard 12-cup muffin tin with paper liners.

Sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt into a large mixing bowl.

Add the egg, milk, vegetable oil, and vanilla extract to the dry ingredients and beat on medium speed for 2 minutes.

Stir in the boiling water by hand until the batter is smooth; note that the batter will be very thin.

Pour the batter into the prepared muffin cups, filling each approximately two-thirds full.

Bake for 18 to 22 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.

Transfer cupcakes to a wire rack and allow to cool completely to room temperature.

Using a cupcake corer or a small paring knife, remove the center of each cooled cupcake, then fill the cavity with 2 teaspoons of strawberry preserves.

In a stand mixer, cream the softened butter until light and fluffy, then gradually add powdered sugar one cup at a time.

Mix in the strawberry puree and beat on high until the frosting achieves a pipeable consistency.

Pipe the frosting onto the cupcakes using a star tip and garnish each with a fresh strawberry.