These are the best cornflake cookies! They have a buttery, caramel flavor, with chewy oatmeal-cookie-like centers, and a nice crunch from the cornflakes, all sprinkled with flaky sea salt.
In a large bowl, cream the butter, brown sugar and granulated white sugar together with an electric hand mixer on high speed until light and fluffy, 2-3 minutes. (You can also use a stand mixer fit with a paddle attachment if you would rather.)
1 cup (224 g) salted butter, softened, 1 cup (220 g) light brown sugar, packed, 1/4 cup (50 g) granulated white sugar
Add in the egg yolks and vanilla extract and mix on medium speed until pale in color and fluffy, 1-2 minutes. (Scrape the sides of the bowl as necessary.)
Scoop the dough with a large, 2 tablespoon capacity cookie scoop. Arrange the cookie dough balls 2 inches apart on a prepared baking sheet. Bake the cookies for 10-12 minutes. (10 minutes gives you chewy cookies, and 12 will give you crispier cookies.)
After baking, let the cookies cool on the cookie sheet for five minutes, then transfer them to a wire rack to completely cool. When the cookies are straight out of the oven, scoot a large circular cookie cutter around them to give them a perfect circular shape. While they're cooling, sprinkle flaky sea salt on top of the cookies.