A high proportion of lemon juice gives curd its intense flavor. Since it is an acidic ingredient, it also prevents the yolks from curdling, eliminating the extra step of tempering. Lemon curd makes a delicious filling for a cake like the one on page 457 but it’s equally welcome spread into a tart shell or on slices of pound cake or Buttermilk Shortcakes (page 433). Gelatin is added primarily to make a sturdier cake filling; leave it out if you are making the curd to serve on its own. Other citrus curds can be made using the formula below; replace 1/2 cup of the lemon juice with other fresh citrus juice and use an equal measure of zest.

　　

Ingredients

makes about 1 3/4 cups

　　2 tablespoons cold water (optional; only if using gelatin)

　　1/2 teaspoon unflavored powdered gelatin (optional)

　　4 large whole eggs plus 6 large egg yolks

　　1 cup sugar

　　Finely grated zest of 2 lemons (about 5 teaspoons) plus 3/4 cup fresh lemon juice (from 5 or 6 large lemons)

　　6 tablespoons (3/4 stick) unsalted butter, cut into small pieces and well chilled

　　

Step 1

Dissolve gelatin (if using) Pour water into a small bowl, then sprinkle with gelatin; let stand until gelatin has softened and all water is absorbed, about 5 minutes.

　　

Step 2

Cook curd In a small, heavy-bottom saucepan, whisk together eggs and yolks. Add sugar and lemon zest and juice. Cook over medium-low heat, whisking constantly, until thick enough to coat the back of a wooden spoon (it should hold a line drawn by your finger), 8 to 10 minutes.

　　

Step 3

Thicken curd Remove pan from heat and add the gelatin mixture (if using), stirring until dissolved. Stir for a few minutes to cool slightly. Stir in butter a few pieces at a time, stirring until smooth after each addition.

　　

Step 4

Strain and chill Strain through a fine sieve into a bowl (to remove any undissolved bits of gelatin and egg), pressing with a flexible spatula to remove as much curd as possible. Press a piece of plastic wrap directly onto the surface to prevent a skin from forming, and refrigerate until set, at least 2 hours (or up to overnight). Whisk until smooth before using.

　　

Ingredients

Step 5

Lemons should feel heavy for their size, with thin smooth skins. Those with thick, bumpy skins are usually less juicy. Before juicing a lemon, roll it on a countertop to soften the membranes slightly before cutting and juicing; this helps it to release more juice.

　　Reprinted with permission from Martha Stewart's Cooking School: Lessons and Recipes for the Home Cook by Martha Stewart. Copyright © 2008 by Martha Stewart. Published by Crown Publishing. All Rights Reserved.Martha Stewart is the author of dozens of bestselling books on cooking, entertaining, gardening, weddings, and decorating. She is the host of The Martha Stewart Show, the Emmy-winning, daily national syndicated program, and founder of Martha Stewart Living Omnimedia, which publishes several magazines, including Martha Stewart Living; produces Martha Stewart Living Radio, channel 112 on SIRIUS Satellite Radio; and provides a wealth of ideas and information on www.marthastewart.com.