A few weeks ago I bought a bag of key limes. While tiny, key limes are prized for their tartness. Being late summer and all, I thought a lime tart would be quite refreshing in this heat!

I was going to make a sable tart dough and fill it with lime curd when I came across this recipe for Key Lime Cocoa Tartlets. The key lime filling is simplified by using a can of sweetened condensed milk, making it a quick recipe, but the chocolate crust is what sets this tartlet apart from others. Key lime and chocolate? Delicious!

It’s a very soft dough, but it survives the pressing and prodding of fingertips into the little tart pans beautifully. The shells remained tender and delicate. After pressing them into their molds I let the dough rest in the refrigerator to relax the glutens. This also prevents the shells from shrinking too much while they bake.

Another note on the chocolate tartlet dough- use the best quality cocoa you can get. I like to bake with high fat cocoa powders, anywhere in the range of 22-24% cocoa fat. You can find good cocoa powders online, such as sites like www.kingarthurflour.com and www.pastrychef.com. They really lend a richness and an intense chocolate flavor to recipes. The first time I used a higher fat cocoa powder I was amazed at its likeness to brownie batter when simply whisked with water.

If you’re feeling a bit betrayed by the fact that cocoa powder can have a high fat content, just consider this:

1. A dessert made with pure, high quality ingredients is going to be very rich in flavor and taste.

2. It is much easier to satisfy cravings with a small sliver of an intensely decadent, delicious dessert rather than a huge slice of a sub-par one that still leaves you lingering for something else.

3. With high quality you always win!

I also loved the combination of key lime and chocolate in these tartlets. It’s easy to fall into the chocolate-orange trap. Citrus flavors are fun and diverse: tangerine, grapefruit, blood orange, Meyer lemon, kumquat…the list goes on.

Top the tartlets any way you wish. I used creme chantilly, a sweetened whipped cream. The actual recipe calls for creme fraiche.

Key Lime-Cocoa Tartlets (New Flavors for Dessert by Williams-Sonoma)

Cocoa Tartlet Dough:

• 1 1/4 cups all-purpose flour
• 1/3 cup unsweetened Dutch-process cocoa powder
• 1/2 teaspoon salt
• 6 tablespoons unsalted butter, cut into cubes, at room temperature
• 1/2 cup plus 2 tablespoons confectioner’s sugar
• 1 large egg, lightly beaten

Whisk the flour, cocoa powder, and salt together in a bowl. In a food processor, combine the butter and sugar and process until blended. Add the flour mixture and process until almost combined, about 8 seconds.

Scrape the sides of the bowl and pulse until the mixture resembles coarse meal. Add the egg and process until the dough comes together. Transfer to a work surface dusted with cocoa and knead 2 or 3 times to bring the dough together; it will be very soft.

Press into a disk, wrap tightly, and refrigerate for at least 1 hour to let the gluten relax. The dough can be chilled or at room temperature when pressing into the tart pans.

Pat the dough into a 6-inch by 9-inch rectangle and cut the rectangle in half lengthwise, then cut each half crosswise into thirds; you should have six 3-inch squares. Place each square in a 3-inch tartlet pan, then dip your fingertips in cocoa powder and press the dough into the bottom and sides of the pans.

Press off any excess dough from around the edges, and use any scraps to fill holes or cracks. Chill the tartlets for 30 minutes in the refrigerator.

Preheat the oven to 375 degrees F. Place tartlet shells on a baking sheet and bake until set, about 10 minutes. Let the shells cool on a wire rack.

Key Lime Filling:

• 1 can sweetened condensed milk (14 ounces)
• 1 large egg, at room temperature
• 2 large egg yolks, at room temperature
• 3 tablespoons white rum
• 8-10 key limes

Whisk together all but 3 tablespoons of the sweetened condensed milk (save the 3 tablespoons for another use), the whole egg, egg yolks, and rum. Finely grate the zest from 3 of the limes, the squeeze 1/3 cup lime juice.

Whisk the zest and juice into the condensed milk mixture. Ladle the filling into the tartlet shells, dividing it evenly, and bake until just set, about 15 minutes. Let cool at room temperature on the baking sheet on a wire rack, then cover with plastic wrap and refrigerate for at least 4 hours or up to 2 days.

When ready to serve, spread with creme fraiche or whipped cream.

Yield: Six 3-inch tartlets