Hey hun. Here is recipe for egg-yolk custard. It makes about 3/4 cup.

2/3 cup milk
pinch ground cinnamon
1 egg yolk
2 tsp white sugar
1 tsp cornflour

Bring milk and cinnamon to a boil in a small saucepan; remove from heat
Whisk yolk, sugar and cornflour in small bowl until combined
Pour milk mixture over yolk mixture, whisking continuously until combined
Return mix to same saucepan, cook stirring over low heat until mixture just boils and thickens
Remove from heat; cover surface of custard with plastic wrap.
Cool to room temp