Thin and crispy oatmeal lace cookies can seem magical if you have never made them before, but they are actually very simple.
Just melt sugar and butter, and then add the oats and flour to make a thin batter. Don’t be scared of how thin it seems!
The cookies spread and caramelize in the oven, creating a thin and crispy network of sugar that's just substantial enough to hold the oats together.
I use thick-cut rolled oats because I think they give more "bite" and substance to the cookies. Look for thick-cut oats in both the cereal section and the baking section - I like Bob's Red Mill oats, personally. It's fine to substitute regular rolled oats if you have trouble finding the thick-cut, though instant or quick-cooking oats might make the cookies too fragile. (But let me know if you try them and what you think!)
When you're melting the butter and sugar together, you don't need to worry about cooking it, checking the sugar temperature, or anything so fussy. You only need to heat them long enough to melt the butter and dissolve the sugar.
Stir a few times as this is happening to make sure the butter and sugar are melting evenly. It's ready when you have a thick brown paste. Also, it's fine if you see some streaks or puddles of separated butter; the butter and sugar don't need to fully combine for this recipe to work.
The other secret to making this cookies is to spread the batter into a thin layer on the baking sheet so the cookies bake evenly.
If you just pile the cookie batter in heaping spoonfuls, the center of the cookie will be thicker than the edges and the cookies won't become fully crispy. You want an even distribution of oats and a thin layer of batter to create the crispy, lacy magic.
Oatmeal Lace Cookies
- 1/2 cup (115 g or 1 stick) unsalted butter
- 1 cup (220 g) packed dark brown sugar
- 2 tablespoons all-purpose flour
- 2 teaspoons vanilla extract
- 1/2 teaspoon kosher salt
- 1 large egg
- 1 1/2 cups (170 g) thick-cut rolled oats (or substitute regular rolled oats)
Preheat the oven to 350F:
Line a baking sheet with parchment paper.
Melt the butter and sugar:
Place the butter and brown sugar in medium saucepan over medium heat. Warm, stirring frequently, until the butter and brown sugar melt into a thick brown paste. It's fine if you see some streaks or puddles of separated butter; the butter and sugar don't need to fully combine.
Mix in the flour:
Remove the pan from heat and stir in the flour, vanilla, and salt. The batter will be very thin. Set aside for 10 minutes to cool.
Mix in the egg and oats:
Once the liquid has cooled (it’s OK if it is still warm, just not piping hot), add the egg and mix with a fork until incorporated. Add the oats and stir until well distributed.
Divide and shape the cookies:
Spoon 1 tablespoon of the batter onto the baking sheet, leaving about 2 inches or more of space between each one. Use the back of a spoon to spread each cookie into a very thin circle, so the oats are in a single layer. If you don't have enough room on one baking sheet, bake the cookies in batches.
Bake the cookies:
Bake in the oven for 8 minutes or until the edges of the cookies start to turn dark golden brown. Remove from the oven and let the cookies cool completely on the parchment paper. The cookies should peel easily from the parchment, but use an offset spatula if any are sticking.
Store in an airtight container for up to 3 days between sheets of parchment paper.