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Old-Fashioned Peanut Brittle

G By Our Grannies' Kitchen Updated Jul 2026 4.8 (287 ratings)
Old-Fashioned Peanut Brittle
Old-Fashioned Peanut Brittle
4.8 / 5
40 pieces

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Ingredients

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  • 2 cups (400 g) granulated or granulated sugar
  • 200 g golden syrup (or light corn syrup)
  • ½ cup (120 ml) water
  • 300 g unsalted roasted peanuts
  • ¼ stick (30 g) butter, cubed, plus extra for the trays
  • 1½ tsp baking soda, sifted
  • 1 tsp vanilla extract and ½ tsp fine sea salt

Method

  1. Get everything ready. Grease two large baking trays well with butter (or line with parchment and grease that) and warm them in a low oven. Cube the butter; measure the vanilla, salt and sifted baking soda into little bowls by the stovetop. The end moves fast — and hot sugar is over 300°F (150°C), so no children underfoot and never taste it.
  2. Dissolve. Sugar, golden syrup and water into a deep, heavy pan of at least 3 liters (it foams later). Medium heat, stirring gently until every grain has dissolved, then clip on a sugar thermometer and stop stirring.
  3. Boil. Boil steadily, without stirring, to 275°F (140°C) — about 10–12 minutes. Wash any crystals off the pan sides with a pastry brush dipped in hot water.
  4. Add the peanuts. Stir in the peanuts and salt and keep cooking, now stirring constantly, until deep amber and 300–310°F (149–154°C) — hard-crack stage. No thermometer? A drip in ice-cold water should set into threads that snap clean; if they bend, keep boiling.
  5. Baking soda. Off the heat, working fast: stir in the butter and vanilla, then the sifted baking soda. It foams up pale gold — that foam is the snap. Stir just until evenly blended, no more.
  6. Pour and stretch. Pour at once onto the warm trays and spread with a spatula. After a minute, when the edges will take a fork, use two forks to stretch the sheet as thin as you can — thin brittle snaps, thick brittle pulls fillings.
  7. Snap. Cool completely, about 30 minutes, then snap into rough shards. Into an airtight tin the moment it is cold — brittle hates damp air.
Granny's tip

Granny always warmed her trays in the oven before she poured — hot toffee spreads twice as thin on a warm tray, and thin is what makes brittle brittle.

Tips for a glassy snap

Hard-crack or nothing

The whole recipe lives at 300–310°F (149–154°C). A drip of syrup in ice-cold water should set into threads that snap clean — if they bend, keep boiling.

Measure everything first

Butter, vanilla and sifted baking soda standing ready by the stovetop before the sugar goes on. The final minute moves far too fast for rummaging in cupboards.

Sift the baking soda, stir briskly

Lumps leave bitter pockets, and the foam is the snap — stir just until it is evenly pale gold, then pour at once before the bubbles settle.

Questions, answered

Why is my peanut brittle chewy instead of crisp?

Nine times out of ten the syrup never truly reached hard-crack stage, 300–310°F (149–154°C), so water was left in the sugar and it set soft. Trust the cold-water test: a drip in ice-cold water should snap, not bend. The other culprit is humidity — brittle drinks moisture from damp air and softens, so make it on a dry day and seal it in an airtight tin the moment it is cold. Chewy brittle can be rescued: melt it gently back down with a splash of water, stirring constantly, and re-boil it to 300°F (150°C).

How should I store peanut brittle and how long does it keep?

In an airtight tin or jar at cool room temperature, with parchment paper between the layers, it keeps 6 to 8 weeks. Never store it in the fridge — condensation forms on the sugar and turns it sticky and grainy. Freezing carries the same risk when it thaws; a well-sealed tin in a dry cupboard is genuinely better.

Can I use raw peanuts instead of roasted?

Yes — that is the truly old-fashioned way. Stir raw shelled peanuts in much earlier, at about 240°F (115°C), and they roast in the boiling syrup as it climbs to hard-crack; it takes a few minutes longer and needs near-constant stirring so they do not scorch. Ready-roasted nuts go in at 275°F (140°C) as written, since they only need warming through. If your peanuts are salted, simply leave out the added salt.

Why do you put baking soda in peanut brittle?

It is the secret of the snap. Baking soda reacts with the hot syrup and releases thousands of tiny carbon-dioxide bubbles, which aerate the toffee so it sets light, porous and shatteringly crisp rather than dense and tooth-breaking. It also lightens the color to that classic honeycomb gold. Sift it first — lumps leave bitter pockets.

From Granny's Pantry

The know-how behind this recipe:

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