01 - In a medium saucepan, combine the heavy cream, whole milk, granulated sugar, and a pinch of salt. Warm over medium heat, stirring gently until the sugar has fully dissolved and the mixture begins to steam. Do not allow it to reach a boil.
02 - Place the egg yolks in a medium mixing bowl and whisk lightly. Slowly drizzle approximately ½ cup of the warm cream mixture into the yolks while whisking vigorously to temper them. Gradually pour the tempered yolk mixture back into the saucepan, whisking continuously.
03 - Cook the mixture over low heat, stirring constantly with a wooden spoon or silicone spatula, until the custard thickens enough to coat the back of a spoon, approximately 5 to 7 minutes. Do not let the custard boil.
04 - Remove the saucepan from heat. Stir in the raspberry extract, lemon extract, vanilla extract, and blue food coloring until fully incorporated and the desired shade of blue is achieved.
05 - Pour the custard through a fine mesh sieve into a clean bowl to remove any cooked egg bits. Allow it to cool to room temperature, then cover with plastic wrap and refrigerate for at least 4 hours or overnight for best results.
06 - Transfer the chilled custard to an ice cream maker and churn according to the manufacturer's instructions until the mixture is thick, creamy, and has soft-serve consistency.
07 - Scoop the churned ice cream into a lidded freezer-safe container, smooth the top, and freeze for at least 2 hours before serving to achieve a firmer, scoopable texture.