scaled down...

1 cup sugar
1/4 cup water
50gm salted butter (cold)
1/2 cup milk

Start in a cold saucepan (small obvly) mix the sugar and water. Constantly stirring at high heat until all the sugar is dissolved, then medium heat until the very bubbly mixture (keep stirring) turns light brown. turn to low heat, add the butter and keep stirring until fully incorporated. Add milk slowly, stirring constantly. if the mixture have thick spots just keep stirring until consistent.

You can reduce the milk amount by half to get a thicker sauce or use evaporated milk for a stronger milk taste. this is runny (because i want to stir it into coffee.)