In the bowl of a stand mixer, combine the cake box mix, flour, sugar, salt and finely chopped lemon zest. Turn on low for about 30 seconds to mix dry ingredients.
In a separate bowl for the wet ingredients, add the water, lemon juice, eggs, oil, vanilla and sour cream.
Pour the wet ingredients into the stand mixer and turn on low for 30 seconds. Then increase the speed to medium-high for 2 minutes.
Fill batter into lined cupcake tins, no more than 2/3 of the way full.
Combine the raspberry preserves and fresh raspberries in a bowl and mix thoroughly.
Add 3-5 drops of the raspberry sauce onto the batter of each cupcake. Using a skewer, gently swirl the raspberry sauce into the lemon cupcake batter until slightly marbled in appearance.
Bake in a 350 Fahrenheit oven for 18 minutes.
Remove from oven let them cool completely before frosting.
For the Frosting:
In the bowl of a stand mixer, combine softened butter and softened cream cheese. Mix on medium-high until very smooth.
Slowly add the powdered sugar on medium speed, in small amounts until incorporated. Then add the vanilla, lemon juice, and finely chopped lemon zest.
Mix on medium-high until smooth.
For the Candied Lemon Zest:
Using a zester (I like to use the type that has 4 or 5 sharp holes so that the zest stays in long strips), zest one large lemon.
In a small saucepan, combine the water, sugar and lemon zest and heat on medium-high until it boils.
Reduce heat slightly. Carefully watch until the sugar is completely dissolved and starts to turn into a syrup. Once the happens, immediately remove the lemon zest with a fork and place it onto a waxpaper lined plate.
Generously sprinkle more granulated sugar onto the zest immediately and roll the zest around in the sugar to completely coat it.
Putting it all together!
Load a piping bag with a large hole opening piping tip and fill it with the Lemon Cream Cheese Frosting.
Pipe two large layers of the frosting onto each cupcake in a circular motion. I like to have to top layer be slightly smaller than the base layer.
Adorn the top of each cupcake with a few sprigs of the Candied Lemon Zest and a fresh raspberry.