I was inspired to make this as a spin on a salad I used to make at my restaurant Brasserie T with blue cheese, grapes and spicy pecans. It was one of the most popular dishes we served, and you'll find the salad in my first book, "American Brasserie". When I started making foams, I found blue cheese foam to be light, intensely flavored, and yet not as rich and heavy as straight blue cheese. The port reduction works nicely and makes this foam fun to serve. Always use a good port -- medium to high-end -- for a reduction. If you wouldn't drink it, don't cook with it. Here I use dry port, but if you have only sweet port, use it.
Put the port wine in a medium-sized saucepan and bring to a boil over medium-high heat. Reduce the heat and simmer for about 25 minutes or until the wine is reduced to a syrup. Remove from the heat and allow the reduction to cool. Transfer to a covered container or squeeze bottle and refrigerate until needed.
Pour the cream into a large saucepan and bring to a boil over medium-high heat. As soon as the cream boils, remove from the heat.
Add the blue cheese and using a handheld immersion blender, puree until smooth. Alternatively, transfer the cream and cheese to a food processor and process until smooth. Strain through a chinois or fine-mesh sieve into a large bowl. Season, to taste, with salt and pepper and set aside to cool at room temperature.
Pour the blue cheese mixture into the chilled canister of a foamer. The amount will fill it halfway. Charge it with 1 or 2 charges. Chill for at least 2 hours before serving.
To serve, shake the foamer vigorously and place a little blue cheese foam on a small plate. Garnish with a drizzle of port wine reduction. If it's too thick to drizzle, let the reduction come to room temperature. Repeat to make 5 to 7 more servings.
Recipe courtesy of Rick Tramonto, "Amuse-Bouche: Little Bites That Delight Before the Meal Begins", Random House, October 2002