1 c. brown sugar
2 tbsp. butter
1 tbsp. flour
1 egg yolk
1 c. milk
1 tsp. vanilla
1/4 tsp. salt

(Best done in a cast iron skillet.) Boil sugar and butter together until soft. Beat the egg yolk well and add it to the flour, milk, vanilla, and salt. Carefully stir a little at a time into the sugar mixture. Cook, stirring constantly, until thick and bubbly.