Soak oats in 2 cups water overnight. Drain before using.
Bring 2-1/2 cups water and salt to a boil. Add soaked oats, stir till boiling. Cover and simmer for 20 minutes, stirring occasionally with your spurtle. In last 5 minutes of cooking time, add molasses, spices and brown sugar.
Custard Sauce
Bring milk, half and half and sugar to scalding (not boiling). Whisk in corn starch.
Meanwhile, whisk the egg yolks. Add 1/2 cup of the hot milk to the eggs, whisking rapidly. Slowly pour eggs into pan, whisking continuously.
Switch to a wooden spoon, stir gently and continuously until custard sauce has thickened slightly. Do not let it boil or eggs will curdle and separate.