190gBritish golden syruplight corn syrup may be substituted (½ cup)
400gold-fashioned rolled oats(4½ cups)
¼tspsalt
Equipment
9-inch square baking pan
Parchment paper
Heavy-bottomed saucepan
Kitchen scale optional, but recommended
Method
Preheat the oven to 350°F (175°C). Line a 9-inch (23 cm) square baking pan with parchment paper, leaving enough overhang to lift the flapjack out once cooled.
Add the butter, light brown sugar, golden syrup and salt to a heavy-bottomed saucepan. Heat gently over low heat, stirring occasionally, until the butter has melted and the mixture is smooth. Avoid bringing the mixture to a boil.
Remove the saucepan from the heat. Add the rolled oats and stir thoroughly until all of the oats are evenly coated in the butter and golden syrup mixture.
Transfer the mixture to the prepared pan. Spread it evenly into the corners, then press it down firmly using the back of a spoon or the bottom of a glass.
Bake on the center rack for approximately 20–25 minutes. The edges should be golden and set and the top should be an even golden color. The center may still look slightly soft when the flapjack is removed from the oven; it will continue to set as it cools.
Don't overbake! Flapjacks continue to firm considerably as they cool. If you wait for the center to become completely firm in the oven, the finished flapjacks can become hard or dry.
Place the entire pan on a wire cooling rack and leave the flapjack in the pan until completely cool, approximately 2–3 hours. It is fragile while warm and needs time for the butter and sugars to cool and set.
Once completely cool and firm, use the parchment paper to lift the slab from the pan. Cut into squares and serve.
Notes
Oats: In the U.S., use old-fashioned rolled oats. These are the closest equivalent to the traditional porridge oats commonly used in Britain. Avoid instant oats, as they will produce a noticeably softer texture.Golden syrup: For the classic British flavor and texture, I strongly recommend using British golden syrup, such as Lyle’s. If you can’t find it in the U.S., you can substitute an equal amount of light corn syrup, although the flavor will be less distinctive and the flapjacks may not hold together quite as well.Storage: Once completely cool, store the flapjacks in an airtight container at room temperature for up to 5–7 days. For longer storage, freeze the individual squares in an airtight container or freezer bag for up to 3 months.Altitude: If you're baking at a substantially lower elevation, the recipe should still work well, although the flapjacks may require a few additional minutes in the oven. Use their appearance rather than the clock as your primary guide: the edges should be golden and the center should be set but still slightly soft.