If you have a cat, maybe you keep a little disposable cup on the side of the bathroom sink, so that your cat can get a fresh drink while you brush your teeth. And maybe at some point you’ve confused your cup with his and accidentally taken your morning blood pressure meds with a swig of the cat’s water, at which point blood pressure meds become moot. His cup usually has little bits of stuff in it.

And maybe you have a bum knee that you slather occasionally with Ultra Strength Ben-Gay after a shower. The lesson of proper order is burned in your memory from painful experience: underwear first, Ben-Gay second. Otherwise, you’re pulling your bloomers up through a layer of fiery liniment that will end up where it was never intended while you dance the watusi.

And maybe you’ve pressed a hotel elevator button repeatedly, wondering why the door doesn’t open, only to be told by people who don’t need bifocals that you’re pressing the fire alarm button.

Not speaking rhetorically here.

All that’s to say that everyone makes mistakes. It’s what you do with the knowledge gained that counts.

However, a salty-sweet, crunchy peanut bar is never a bad idea.

Crunchy Peanut Bar, adapted from The Good Cookie, by Tish Boyle, © 2002 by Tish Boyle, published by John Wiley & Sons, Inc., of Hoboken, New Jersey. I saw this recipe first in a compendium published by Food & Wine magazine (Best of the Best hardback series, volume 6). I liked this cookie so much that I bought the cookbook it came from.

Crust

1/2 cup (1 stick) unsalted butter, softened

1/2 cup packed light brown sugar

1 1/4 cups all-purpose flour

1/2 teaspoon salt

Topping

4 tablespoons (unsalted) butter

2/3 cup light corn syrup

1 10-ounce package peanut butter chips

2 teaspoons vanilla extract

2 1/4 cups (12 ounces) salted peanuts

Preheat oven to 350°F. Lightly coat a 9×13-inch pan with non-stick spray.

To make the crust, put the butter and brown sugar in a medium bowl and beat together with a hand-held electric mixer for about 1 minute. Sprinkle flour and salt over the top and work into the butter mixture with the mixer at low speed, just until crumbles form. Pour the mixture into the prepared pan and press evenly over the bottom to form the crust. Prick all over with a fork, then bake until the edges are golden brown, 15-18 minutes. Let cool while you prepare the topping. (Keep the oven on.)

To make the topping, combine the butter, corn syrup, and peanut butter chips in a saucepan over medium heat. Stir constantly until the mixture is smooth, taking care not to let it scorch. (The peanut butter chips seem to take forever to melt.) Remove from heat and stir in the vanilla. Pour mixture over the cooling crust and spread with a spoon or offset knife to form an even layer, edge to edge. Sprinkle the peanuts over the top, pressing them gently into the topping so they’ll adhere. Return the pan to the oven and bake for another 12-15 minutes, until the topping is bubbly.

Transfer pan to a wire rack and let cool completely. Cut into bars to serve.