My great-aunt Alice was in her 90s when I was still learning how to count, but even I remember she made awesome peanut brittle. Apparently it was a family recipe, because my grandmother Dorothy (Alice’s sister) shared a very similar recipe in the Fillmore, IL cookbook. Here is the version my mom had on a note card, most probably Dorothy’s. I’ve added some information from the cookbook page below.

1 1/2 lbs. sugar
2/3 lb. glucose (corn syrup)
1 scant pint of water (2 cups)
1 lb. nuts (chop larger-sized nuts so the brittle is easier to spread thinly.)
2 ounces butter (1/2 stick)
1 teaspoon vanilla
1 tablespoon soda
1/2 teaspoon salt

Cook sugar, glucose, and water until it threads (light brown color).

While that’s cooking, prepare a few square feet of clean granite/quartz/marble countertop or porcelain surface by greasing with butter. This should be a flat, durable surface that can withstand molten sugar and scraping.

Add the nuts and butter and cook until the batch browns to one’s color taste (medium brown — if you use peanuts, they should pop open). Watch very carefully at this point.

To cook sugar to the “hard crack” stage for brittle, use a candy thermometer and wait for the batch to reach 300F, as seen in the photo below. That is also the color to aim for. You may not get a high reading from the thermometer while the mix is low in the pot, but it will pick up once you add the butter and nuts. Don’t stir the liquid too much. Use a wet brush to remove hardened drops of condensation from the edges of the pot.

The next steps will move really quickly, so read ahead so you can act fast!

When it’s the right color, remove from the heat and add vanilla, salt, and soda. Stir and pour out onto buttered marble slab or porcelain table top. Try to spread it out from the pot as you’re pouring. Once it’s on the slab, it’s not going to spread much at all and you’ll get stuck with some really thick brittle.

When it’s cooled, use a metal spatula to pry chunks of brittle off the surface. Break up larger pieces. Store in an airtight container between layers of wax paper.

But wait — there’s more!

There was an additional recipe card in the same plastic slipcover with Mom’s copy of the recipe above. This is in a different hand with less information; it might be Aunt Alice’s version. 

1 cup white syrup
2 cups white sugar
1/2 cup water

Cook to hard stage. Add:
2 cups raw peanuts
2 lbs butter
1 tsp salt
1 tsp soda
vanilla

In case you can’t find glucose or want to avoid “white syrup” — here’s Martha Stewart’s recipe.