In a small pot over medium heat, place the butter, and melt it. Then add in the peanut butter and the sugar and stir everything well until it's all melted together.
In a large bowl, place your graham cracker crumbs and corn flakes.
Remove the butter/peanut butter/sugar mixture from the heat and stir in the vanilla.
Pour the entire contents over the graham crackers and corn flakes. Stir well to combine.
Press the mixture into an 8"x8" pan, then place in the refrigerator for at least an hour to set.
Melt the chocolate over a double boiler. Once the chocolate is melted, add a little milk, a few tablespoons at a time, until it gets to a pourable consistency. (this is the tricky part--I can't give you real measurements here, you have to kinda wing it). Pour the chocolate over the peanut butter base and sprinkle the whole thing with a pinch or two of finishing salt. Place in the fridge to set.
Cut into 12-16 squares.
This bar tastes great frozen. Store in the freezer and pull one out 5 minutes before eating.