Step 1: Make the Custard Base

1. Whisk egg yolks and sugar in a bowl until smooth and pale.
2. Heat milk and salt in a saucepan over medium heat until it simmers (do not boil). Gradually whisk ½ cup of the hot milk into the egg mixture to temper it.
3. Pour the tempered mixture back into the saucepan and cook on low, stirring constantly, until thick enough to coat the back of a spoon (about 5–7 minutes). Avoid overheating to prevent curdling.
4. Strain into a bowl, stir in heavy cream and vanilla, and cover with plastic wrap touching the surface. Chill for at least 3 hours.

Step 2: Prepare the Honeycomb Toffee

1. In a saucepan over medium heat, melt sugar and golden syrup, stirring occasionally until golden amber (300°F if using a thermometer).
2. Remove from heat and quickly stir in baking soda until foamy. Pour onto a parchment-lined baking sheet and let harden for about 20 minutes. Break into small pieces.

Step 3: Churn and Freeze Ice Cream

1. Pour chilled custard into an ice cream maker and churn according to manufacturer instructions (about 20–25 minutes).
2. In the last two minutes of churning, fold in honeycomb pieces gently to maintain their crunch.
3. Transfer to a freezer-safe container, press plastic wrap onto the surface, and freeze for at least 4 hours or until firm.