POTS DE CREME:

1. Place chocolate in medium heatproof bowl; set fine-mesh strainer over the bowl and set aside.

2. Whisk the yolks, sugar and salt in medium bowl until combined; whisk in the heavy cream and half-and-half. Transfer mixture to medium saucepan. Cook mixture over medium-low heat, stirring constantly and scraping bottom of pot with wooden spoon, until thickened and silky and custard registers 175 to 180 degrees on an instant-read thermometer, 8 to 12 minutes. Do not let the custard overcook or simmer.

3. Immediately pour custard through the strainer over the chocolate. Let the mixture stand to melt chocolate, about 5 minutes. Whisk gently until smooth, and then whisk in vanilla (or Kahlua) and espresso (if using). Divide mixture evenly among eight small cups. Gently tap against counter to remove air bubbles.

4. Cool pots de creme to room temperature, and then cover with plastic wrap and refrigerate until chilled, at least 4 hours or up to 72 hours. Before serving, let the pots de creme stand at room temperature 20 to 30 minutes.

FOR THE WHIPPED CREAM: Using hand mixer or standing mixer fitted with whisk attachment, beat the cream, sugar and vanilla on low speed until bubbles form, about 30 seconds. Increase the speed to medium; continue beating until beaters leave trail, about 30 seconds longer. Increase the speed to high; continue beating until nearly doubled in volume and whipped cream forms soft peaks, 30 to 45 seconds longer.

5. Dollop each pot de creme with about 2 tablespoons whipped cream; garnish with cocoa or chocolate shavings, if using. Serve.

(James Moore writes the blog Cook Like James. One for the Table is Amy Ephron's online magazine that specializes in food, politics and love. http://www.oneforthetable.com/.)