Preparation

Place raspberries in a food processor fitted with the metal "s" blade or in a blender (if using a blender, 2 cups at a time for best results). Process until completely puréed and smooth. Press raspberry purée through a fine mesh sieve or chinois with a wooden spoon or spatula. Discard seeds -- you will have approximately 2 cups red raspberry purée; reserve. Place the sugar and 1¼ cups of the half-and-half in a 2½ quart saucepan with a heavy bottom. Bring to a simmer over medium heat and stir to dissolve the sugar. Keep warm over low heat. Place the egg yolks in a medium bowl and whisk until thickened, about 2 minutes (can use a hand or stand mixer fitted with the whip on low speed). While whisking, add ½ cup of the hot half-and-half/sugar mixture and whisk until blended. Stir the egg mixture back into the saucepan; increase heat to medium. Stir the mixture constantly with a wooden spoon, until the mixture is thickened like a custard sauce and registers 180 °F when checked with an instant-read thermometer. Stir in remaining half-and-half, powdered milk and heavy cream. Strain the mixture through a fine mesh strainer; stir in reserved raspberry purée, vanilla, and food coloring. Cover and refrigerate at least 6 hours before continuing. Turn the machine on; pour mixture into freezer bowl, and let mix until thickened, about 20 to 25 minutes. The gelato will have a soft, creamy texture. If a firmer consistency is desired, transfer the gelato to an airtight container and place in freezer for about 2 hours. Remove from freezer about 15 minutes before serving.