Heat butter, sugar, vanilla and salt in a nice sturdy saucepan on med heat until butter is melted. Turn temp up to med-high and stir constantly until mixture comes to a boil. Set your timer for 5 minutes and DO NOT let ANYTHING disturb you while you stir. You must keep stirring your butter/sugar mixture so that it does not burn. And you must use a WOODEN spoon. Keep stirring until your timer goes off. It may even smoke a tiny bit and that is ok. If you are really concerned, lift you pan off of the burner (while you are still stirring) to remove it from the heat, but still stir until your timer goes off. You are looking for toffee that is the color of a brown paper bag. Not tan or beige, but BROWN. Immediately pour hot toffee onto your foil-lined baking sheet. The toffee will be about 1/4-1/2″ thick. Do not scrape the bottom of the pan. As you pour, the bottom will brown and you don’t want that in your toffee. Let toffee cool. It should harden within a couple of minutes. Melt Ghirardelli bricks or wafers, Wilton melting chocolate, chocolate chips, or any other variety of white melting chocolate in the microwave at 30-second intervals until smooth. Spread across your toffee with a small spatula or butter knife. Sprinkle liberally with a mixture of cinnamon and sugar while white chocolate is still wet. After it has set up, break toffee into pieces.