01 - In a medium saucepan, combine the whole milk, heavy cream, granulated sugar, and salt. Set over medium heat, stirring frequently, until the mixture is steaming and the sugar has fully dissolved. Do not allow it to boil.
02 - Place the egg yolks in a separate mixing bowl and whisk briefly. Slowly pour 1/2 cup of the hot dairy mixture into the yolks while whisking vigorously to temper them and prevent scrambling.
03 - Gradually pour the tempered yolk mixture back into the saucepan, whisking constantly. Cook over medium-low heat, stirring continuously, until the custard thickens enough to coat the back of a spoon, approximately 5 to 7 minutes.
04 - Remove the saucepan from the heat. Stir in the vanilla extract, raspberry extract, lemon extract, and almond extract until well combined. Add the blue food coloring, starting with 3 drops and adding more as needed, mixing until the color is uniform and vibrant.
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 tightly with plastic wrap and refrigerate for at least 3 hours or until completely chilled throughout.
06 - Pour the chilled custard into an ice cream maker and churn following the manufacturer's instructions until it reaches a soft-serve consistency. Transfer the churned ice cream to a freezer-safe container, cover, and freeze for 1 to 2 hours until firm.