In a bowl, whisk egg yolks and sugar until pale and smooth.
In a saucepan, heat cream, milk, and salt until warm (not boiling).
Slowly add warm cream to the egg mixture while whisking (tempering).
Pour mixture back into the saucepan.
Cook over low heat, stirring until slightly thickened.
Remove from heat and stir in vanilla, almond, lemon, and raspberry extracts.
Add blue food coloring and mix well.
Chill mixture in the refrigerator for 3–4 hours.
Churn in an ice cream maker according to instructions.
Freeze for 2–3 hours until firm.