My grandfather's chocolate fudge - and peanut butter fudge

This is a family recipe. I don't know if my Granddaddy Taylor made it up or found it in a newspaper or elsewhere, but it's definitely the best chocolate fudge ever. My mother worked nights and I made it for my sisters and brothers. I didn't have a candy thermometer and it was usually didn't harden and was eaten with spoons. My mother didn't like us making fudge while she was working because we were wasting her ingredients, so she locked up them up in a cabinet with a combination lock. Didn't take us long to figure out the combination. Then she got a regular lock that worked with a key. Didn't take us long to find a key that fit. Then she got a commercial lock that we couldn't figure out, so we unscrewed the hinges on the door. If not for this, I probably would have completely forgotten about my grandfather's fudge and the recipe would have been lost. Thank you, Mom.
The recipe:

2 cups sugar
1/2 cup milk (believe it or not, nonfat milk works best)
1/2 cup light Karo syrup (light in color, not calories)
1/2 teaspoon salt
2 ounces Baker unsweetened chocolate
1/2 stick of cold butter
1 teaspoon vanilla
1 cup toasted pecan pieces

Butter a small 8" x 8" pan or equivalent. Put the sugar, milk, Karo, and salt in a pot. Mix until all ingredients are combined. Add the unsweetened chocolate. Put in a candy thermometer and be careful that it doesn't touch the bottom. Put it on the stove and turn the burner to medium. Do not do anything else. Do not stir. Do not turn the heat up or down. Do not play games on the computer or answer your phone. Do not do any housework. Instead, stare at the thermometer. The second it gets at the soft ball stage, remove it from the heat. Add the vanilla. After it's finished sizzling (about ten seconds), add the butter. Stare at it until the butter is completely melted. Stir with a wooden spoon until all the butter is combined with the chocolate mixture. This usually takes about 5-10 minutes. Do not stop stirring. When fully combined, add the pecan pieces and stir them in. Then pour the mixture into your pan. When it is starting to harden, which should be within about ten minutes, use a knife to "draw" the pieces vertically and horizontally. Then, when it completely hardens,  use a dough scraper to cut it.

Note: Candy thermometers differ. Get a good one. With mine, I have to remove the fudge just slightly before it gets to the soft ball stage or it will get too hard. A friend has to go a little past the soft ball stage for best results. So if your first batch isn't perfect, let it go below or above the soft ball stage next time.

For peanut butter fudge - follow all directions exactly, but leave out the unsweetened chocolate and pecans. Add 3/4 cup extra chunky peanut butter at the end when you would add the pecans to the chocolate fudge.