Chill the KitchenAid mixing bowl in the freezer for at least 15 hours.

Whisk together egg yolks and 1/4 cup of granulated sugar in a mixing bowl. Heat whole milk in a saucepan until it reaches 165°F.

Slowly drizzle the hot milk into the egg yolk mixture while whisking continuously, then return to the saucepan and cook until thickened.

Brew a strong cup of coffee and let it cool slightly.

Combine the tempered egg mixture, cooled coffee, heavy cream, vanilla extract, and salt in a bowl. Stir until blended and refrigerate for 4 hours.

Pour the mixture into the KitchenAid bowl and churn on medium speed for 25-30 minutes until soft-serve consistency.

Transfer churned ice cream to a container and fold in chopped toffee candy.

Cover and freeze for a couple of hours until firm.