I was hired to make two types of cupcakes for a Latin/Mexican themed baby shower – Key Lime Pie and Tres Leches. They were serving tacos with three kinds of meat, all the toppings, chips, guacamole, and salsa. I did a little internet research and found some recipes for key lime pie cupcakes but they had no filling… no key lime pie filling! I tested a few cake recipes and made a stove-top cooked pie filling and these are, as my dad calls them, “extra” cupcakes. While delicious any time of year, they would be especially good on a summer day.
Lime cupcake, filled with Key lime pie filling, topped with whipped cream frosting, a sprinkle of graham cracker crumbs, lime zest and a Key lime slice.
Tips & Tricks: You can use regular limes or even bottled lime juice for these cupcakes; however, Key limes have a much stronger citrusy/pucker face/zip to them that would be missed if skipped. Even if you just use half the juice from Key limes, these will be that much better. These cupcakes will last 2-3 days if kept in a refrigerator in a air tight container, though they do taste best day-of or next-day. The gelatin stabilized whipped cream frosting is great, because it keeps the same light texture of whipped cream, but holds its shape much better. Once set, the frosting can be touched and it’s not sticky, yet tastes just like whipped cream.
Key Lime Pie Cupcakes
makes 24-26 cupcakes
Cupcake Ingredients
12 tablespoons (1 ½ sticks) unsalted butter, room temperature
1 ½ cups sugar
¾ cup sour cream
1 teaspoon vanilla
3 teaspoons Key lime zest
6 egg whites, save the yolks for the filling
2 ½ cups flour
4 teaspoons baking powder
½ teaspoon salt
½ cup milk
½ cup Key lime juice
Key Lime Pie Filling Ingredients
½ cup Key lime juice
1-14 oz. can sweetened condensed milk
6 large egg yolks, saved from the cupcakes
pinch of salt
Whipped Cream Frosting Ingredients
½ cup cold water
2 teaspoons (1 packet) unflavored gelatin
2 cups heavy cream
⅓-½ cup powdered sugar
1 teaspoon vanilla
Garnish (Optional)
1 graham cracker, crushed
Key lime zest
Key lime slices
Cupcake Directions
- Preheat the oven to 350 degrees F. Line cupcake tins with cupcake liners.
- In the bowl of a stand mixer, cream butter and sugar until light and fluffy – about 3-4 minutes.
- Add sour cream, vanilla and zest, mixing until combined. Scrape down the bowl to insure full incorporation.
- Add the egg whites in 2 parts, mixing on medium-low until combined. Scrape down the bowl.
- Whisk the flour, baking powder and salt in a medium sized bowl.
- Stir together the milk and lime juice.
- Add half of the dry ingredients to the stand mixer and mix until just combined.
- Follow up with the milk mixture, mixing until just combined and then add in the remaining dry ingredients. Mix until well combined.
- Using a large cookie scoop (Oxo, ~3 Tbsp.), portion the cupcake batter into the lined tins.
- Bake in the pre-heated oven for 15-17 minutes, until a toothpick comes out clean.
- Remove from the oven and cool for 2-3 minutes, then remove them from the tin and cool completely on a cooling rack.
Key Lime Pie Filling Directions
- While the cupcakes are baking, make the pie filling. Pour about 2″ worth of water into the bottom pan of a double boiler and set over medium-high heat.
- In the top bowl of the double boiler, whisk together all the pie filling ingredients until well combined.
- With the water simmering below, whisk the pie filling mixture until it thickens to a custard-like consistency, leaving whisk lines through the mixture – about 5-7 minutes, maybe longer. Do not stop whisking or the filling touching the bottom of the bowl will cook too much.
- Immediately remove it from heat and place in a clean bowl or piping bag. Cover the bowl in plastic wrap and let cool in the fridge for 30-45 minutes. It should be cool by the time the cupcakes are baked and cooled.
Frosting & Assembly Directions
- Frosting: Mix the cold water and gelatin in a small bowl and let sit for 5 minutes.
- Microwave the gelatin mixture for 1 minute, stir and then set aside for 10 minutes to cool.
- Assembly: While the gelatin is cooling, take the cooled cupcakes and use a small knife to cut a triangle shaped cone from the top of the cupcake. It should be about ½” deep and ¾” wide. Repeat with remaining cupcakes
- Take the cooled Key lime pie filling and pipe (or spoon) it into the top of the cupcakes.
- Frosting: In the bowl of your stand mixer, fitted with the whisk attachment, beat the heavy cream to soft peaks.
- Add in the powdered sugar, vanilla and continue to mix on medium-low.
- Slowly pour in the cooled gelatin mixture to the soft beaten heavy cream, beating for a few more minutes until medium-stiff peaks are formed. Use immediately.
- Assembly: Fill a piping bag, fitted with a large round tip, with the whipped cream frosting and pipe little mountains of frosting on top of the cupcakes, covering the pie filling, all the way to the edges of the cupcake.
- Garnish with a sprinkle of crushed graham crackers around the edge, some lime zest and a little slice of Key lime.
- When consuming the cupcake, squeeze the slice of Key lime for an extra hit of lime tartness!
