1. To make the curd: In a medium saucepan, whisk together the sugar, cornstarch, and salt. Whisk in the egg yolks, lime zest, and juice. Bring to a boil, over medium-high heat. Whisk constantly, and cook for about 1 minute. Remove from heat, whisk in sweetened condensed milk, and bring back to a boil. Remove from heat again, and strain the mixture through a sieve. Add in butter, and whisk until smooth. Cover with plastic wrap, and chill for at least 3 hours, or overnight. Now whip up the heavy cream, until stiff peaks, and fold it into the curd. And refrigerate the mixture while we make the cream puffs.

2. To make the choux pastry: Preheat the oven to 450 degrees F, and line two baking sheets with parchment paper. In a medium saucepan, bring butter, sugar, salt, and water to a boil. Remove from heat and immediately stir in the flour with a wooden spatula. Cook over medium-high heat, stirring constantly, for about 3 minutes, until the mixture pulls away from the sides. Remove from heat, and beat with an electric hand mixer, to let it cool slightly, for about 2 minutes. Add in 4 large room temperature eggs, one at a time, beating until fully incorporated. Once it’s done, the batter should be slightly sticky, smooth, and shiny. Transfer that to a piping bag, fitted with a plain round tip, and pipe into rounds about 1 inch in diameter, and 1/2 inch high. If you get peaks while piping, dip your finger into the water, and smooth out the tops. Brush with egg wash, and right before baking, reduce your oven to 350 degrees F. Bake until lightly golden brown, for about 25-30 minutes. Transfer to a cooling rack to let cool completely.

3. To make the Key Lime Glaze: Whisk together powdered sugar, key lime zest, and lime juice. Add more powdered sugar/lime juice if needed for the right dripping consistency.

4. Assemble: Dunk the tops of each cream puff into the glaze, and let that fully harden, for about 30 minutes. Transfer the whipped cream key lime curd to a piping bag, with a 1/2 inch plain tip. Insert into the bottoms of the cream puffs, and fill. Enjoy!