Preheat oven to 350 degrees. Line a 12-cup muffin tin with cupcake liners. Melt unsweetened chocolate in a small microwave-safe bowl in 15-second intervals, stirring between intervals until melted and smooth. Set melted chocolate aside.
In a medium bowl, mix together flour, cocoa powder, baking soda and salt. Set aside.
In a large bowl, use an electric hand mixer to mix together sugar and butter until smooth and creamy.
Mix in egg, egg yolk, and vanilla extract. Blend in melted chocolate and then the sour cream.
While mixing on low speed, slowly add half of the flour mixture until well combined. Then add the remaining half of the flour mixture.
Carefully add about 1/5 of the boiling water at a time into the batter, mixing after each addition. Once all the boiling water has been blended into the mixture, begin to mix on medium-low speed for 1 minute.
Divide the batter into the prepared muffin cups, filling each about 3/4 full. Bake for 17-20 minutes.
Remove the cupcakes from oven and transfer them to a cooling rack. Cool for 15-20 minutes.
Once cupcakes are cool, frost with strawberry buttercream frosting and top with chocolate-covered strawberries. Store cupcakes in an airtight container in the refrigerator.
Place freeze-dried strawberries in a small resealable bag. Secure the bag and crush dried strawberries into a fine powder using a rolling pin. Sift through a fine mesh sieve into a medium bowl to remove seeds and clumps. Set aside.
Next, strain fresh strawberry purée through the fine mesh sieve. Measure out 3/4 cup. Pour the 3/4 cup into a small saucepan and set over medium-low heat.
Simmer purée, stirring occasionally until reduced to a 1/4 cup, about 15-20 minutes.
Pour reduced purée into a small bowl. Then place in the freezer until cooled, stirring occasionally. Don't let purée freeze.
In the bowl of an electric stand mixer fitted with a whisk attachment, whisk butter until smooth and fluffy.
Mix in powdered sugar, cooled strawberry purée, freeze-dried strawberry powder, lemon juice, and vanilla. Blend until frosting is creamy. Add red food gel if desired.
Melt chocolate in a small microwave-safe bowl in 15-second intervals, stirring between intervals until melted and smooth.
Dip strawberries in chocolate and let excess chocolate run off. Place each strawberry on a baking sheet lined with wax paper or Silpat. Allow dipped strawberries to cool. Then transfer each one to a cupcake.
For best results, serve cupcakes within the first day at room temperature.
To achieve the swirling effect of the frosting, use a decorating bag fitted with Wilton 1M tip.
These essential baking tools will come in handy when preparing this lovely dessert.