Check out this easy free from recipe for Dairy and Gluten Free Creme Patissiere which you can use in your baking.
Place the milk into a small saucepan and bring to the boil. While the milk is heating up, beat together the egg yolks, caster sugar, cornflour and vanilla extract in a measuring jug.
When the milk has boiled pour into the measuring jug while whisking continuously. Return the milk to the saucepan and bring to the boil, stirring continuously, until it thickens and boils. Chill the creme patisserie before use.