The Smoothest Ice Cream Is Made with Liquid Nitrogen

Robyn Sue Fischer, founder of the innovative San Francisco ice cream shop, Smitten Ice Cream, made to order, invented the ultimate cop's delight: ice cream with coffee and doughnuts. She starts making ice cream from scratch, using a base of heavy cream, salt, sugar, and coffee grounds whipped together in a large saucepan. She lets the coffee brew in the cream for 10 minutes over medium heat, then filters the mixture to remove the coffee grounds. (Note: Fischer uses only the best ingredients in her ice cream and swears that the blue bottle makes a creme de la creme.) After the thick, creamy mixture cools, you can put it in the ice cream machine at home, but Fischer quickly freezes the liquid in a machine she designed herself, using liquid nitrogen. A self-proclaimed science buff, Fischer spent two years in a basement workshop with a retired engineer, inventing a patented Smitten ice cream machine that she calls the Brrr. In an effort to learn more about the formation of ice crystals, she discovered that the colder the ice cream is frozen, the finer the ice crystals become. And the smaller the ice crystals, the smoother the product gets. This insight led her to liquid nitrogen, which freezes at -321 ° F. Her machine uses liquid nitrogen to freeze ice cream in less than 30 seconds. During the Great Recession, in 2009, Fischer started selling ice cream from a rickety red van in San Francisco. She let her fans know where to find her using Twitter, and usually ended her tweets with the words " Come and get it before it sells out — or before the cops get here." Now that she's outgrown her habits and settled into seven stores on the West Coast, she serves the cop's breakfast in the form of ice cream with coffee and doughnuts. Ice cream for breakfast? We're on our way." Ice cream with coffee and donuts
Combine ground coffee, salt and sugar in a large saucepan. Whisk thoroughly, then add half and the first amount of heavy cream, making sure that the coffee grounds do not stick to the walls of the mold.Bring the mixture to a boil (small bubbles will start to form around the edges of the mold) over medium-high heat, stirring occasionally. Watch carefully — do not let it boil over. As soon as it boils, remove from heat.Remove from heat, cover and let stand for EXACTLY 10 minutes. Set a timer.Slowly pour the mixture through a fine sieve (or chinois) into a large bowl or pot. Squeeze out the dough with medium pressure, using a wooden spoon or ladle to extract the liquid. Do not push too hard and do not try to squeeze out every last drop of liquid, as this will make the base bitter.Add vanilla and instant espresso powder to the mixture. Whisk or blend with an immersion blender until smooth. Refrigerate until completely cooled.To prepare the base for ice cream, mix the milk, a second amount of heavy cream and a second amount of sugar. Heat over medium-high heat, stirring regularly, until the mixture boils. Remove from heat.Place the bowl on an ice bath (a large container or bowl filled with ice and enough water to allow the ice to move freely) and stir occasionally until it cools.Whisk the ice cream base with the second coffee mixture.Freeze the combined base according to the ice cream maker's instructions.While the ice cream is still soft, fold the donut slices into it. Don't mix too much.Allow to set until solidified.