To make the ice cream, combine heavy cream, milk, sugar and salt in a large saucepan over medium heat. Stir until sugar has dissolved, about 5 minutes.

Meanwhile, whisk the egg yolks in a small bowl until smooth. Whisking constantly, slowly whisk about one cup of the hot cream into the yolks, then whisk the yolk mixture back into the saucepan with the cream. Add vanilla extract and continue cooking, stirring gently until the mixture is thick enough to coat the back of a spoon (about 170F degrees). 

Strain through a fine-mesh sieve into a bowl. Let cool to room temperature, then cover cling wrap, placing it right on top of the mixture so that there isn't a layer of air. Chill in the fridge for 4 – 6 hours or overnight. 

Churn in an ice cream machine according to manufacturer's instructions. Store in air-tight container and freeze for at least 4 hours before assembling the sandwiches.

While the ice cream is in the freezer, make the funfetti sugar cookies according to this recipe from Sally's Baking Addiction. Let cool. Take a large scoop of ice cream and sandwich it between 2 cookies. Enjoy immediately or return to the freezer before serving.