Preheat oven to 350 degrees F. Line 2 12-count muffin pans with cupcake papers.
Add cake mix, water, lemon juice and lemon zest to the bowl of a stand mixer. Beat on low for about 30 seconds, then at medium speed for about a minute until the batter is nice and fluffy.
Using an ice cream scoop, divide batter into 2 12-count, paper lined muffin pans.
Bake for about 15-18 minutes, until tops are golden brown and dry.
Chill the bowl and beaters of your mixer for 30 minutes in the freezer or fridge.
Pour heavy cream, powdered sugar, gelatin and vanilla in the bowl and whip on medium high for about 2 minutes, until fluffy and thick. Stir in lemon zest and half of the lemon juice. Taste, and add more lemon juice as needed.
Pipe onto cupcakes using a piping bag. Sprinkle with candy sugar crystals or non-perils.
If you want more of a yellow color so people really get the idea the frosting is lemon flavored, go ahead and add a few drops of yellow food coloring. I added zest and white sugar crystals to mine, but you have to be careful adding zest like that as it can be an overly bitter bite.