Directions

• For the lemon pastry cream
• Peel the lemon as you’d peel a cucumber, making sure to get the yellow peel only and not the white pith beneath, because the pith would be too bitter. Leave the peel pieces as is without chopping them.
• In a medium saucepan, warm the milk and lemon peel on medium heat, paying attention not to boil them. Place the egg yolks in a medium bowl and whisk them with the sugar. Add the cornstarch, and whisk until well combined. 
• Once the milk is warmed, pour it over the yolk mixture, one third at a time – leave the lemon peel, it will continue to flavor the pastry cream. Mix well. 
• Put the cream back on the medium heat and mix well with a whisk until it thickens. Pass through a sieve to eliminate the lemon peel. Leave it to rest overnight in the refrigerator with plastic wrap making contact between the plastic wrap and the surface of the cream.
• For the pistachio cupcakes
• Preheat the oven to 350°F. Line a cupcake pan with 12 baking cups.
  Place the sugar and pistachios in a food processor and process until the pistachios are finely ground. Set aside.
• Melt the butter in a microwave. Keep the butter warm; do not allow it to sit and cool off. In a medium bowl, whisk the eggs and egg whites until lightly foamy.
• Pour the warm butter into the eggs slowly, so that the mixture tempers and the eggs do not scramble. Mix well.
• Add the milk, vanilla, glycerin, and salt. Mix until well combined. Add the flour and baking powder to the pistachio mixture. Add to the batter. Mix well until smooth.
• Scoop the batter into the prepared baking cups, filling them two thirds of the way.
  Bake in the middle of the oven for 20 to 25 minutes, rotating the pan halfway through. The cupcakes are done when the centers spring back when you touch them.
  Remove the cupcakes from the oven. Let cool completely.
• For the American raspberry buttercream
• Puree berries with granulated sugar in a food processor until smooth. Pass mixture through a fine sieve into a bowl, pressing on solids to extract as much liquid as possible.
• In another bowl, beat butter on medium-high speed until pale and fluffy, about 2 minutes. Reduce speed to medium and add confectioners’ sugar, 1/2 cup at a time, beating well after each addition and scraping down sides of bowl as needed. Beat in berry puree. Frosting can be stored in refrigerator up to 2 days; bring to room temperature and beat on low speed until smooth again before using.
• To assemble
• Remove the cooled cupcakes from the pan. With the cupcake coring tool, or with a knife, make a whole in the center of the cupcake, making sure that there is at least 1/4 inch remaining at the bottom of the cupcake.
• Quickly mix the lemon pastry cream and place it in a small pastry bag. Cut a corner and squirt the cream in the center of the cupcake. Close the hole with the top of the cake you removed earlier.
• Place the buttercream in a piping bag with a star tip. Decorate the cupcake, and place a fresh raspberry and pistachios on top, if you’d like.