Preheat oven to 350 and line a 12 count muffin tin with paper liners, set aside,
In large bowl or bowl of a stand mixer beat together your butter and sugar until light and fluffy.
Add your eggs and extracts, lemon juice and zest and continue to mix until blended.
In a medium bowl sift together your flour and baking powder.
Alternate adding your dry ingredients and milk into your butter mixture in about 3 separate additions. Making sure to mix well after each addition.
Add your batter evenly to prepared muffin liners and bake for about 20 minutes or until center when poked with toothpick comes out clean.
Let cool in pan for about 5 minutes before removing to wire rack to cool completely.
Meanwhile to make buttercream, in sauce pan add your raspberries and lemon juice and heat on medium high until berries get soft and are easy to mash with spoon. Reduce head and continue stirring off and on until they have reduced and they can coat the back of a spoon.
Let cool completely (putting in freezer will speed up the process).
In large bowl add your butter and shortening and beat together until light and fluffy.
Once cooled add your raspberry sauce and beat until incorporated.
Adding 1 cup at a time pour in your powdered sugar and mix, keep adding powdered sugar until desired consistency is reached.
Add your buttercream to a piping bad fitted with a large start tip and pipe onto cupcakes.
Decorate with decorative sugar and lemon slices if desired