1⁄2 pound (2 sticks) unsalted butter, at room temperature, plus more for the pan
2 cups sugar
2 large eggs
1⁄2 cup grapeseed or other neutral oil
11⁄2 teaspoons vanilla extract
3 cups all-purpose flour
1 teaspoon kosher salt
1 teaspoon baking soda
1⁄2 cup whole milk
1. Heat the oven to 350°F. Grease a 9 × 13-inch baking pan.
2. Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and cream on high until homogenous, about 3 minutes. Add the eggs, oil, and vanilla and mix until just combined, about 1 minute.
3. Add the flour, salt, and baking soda, mixing until just combined, about
30 seconds. Mix in the milk until just combined, about 30 seconds.
4. Spread the dough in an even layer in the prepared pan. Sprinkle any classic, radioactive, or themed sprinkle to top the cookie slab just before baking.
5. Bake for 20 to 25 minutes for a slightly underbaked cookie (which is how I like it), or for another 3 to 5 minutes if you’re a firm cookie fan. Cool completely in the pan before cutting into squares.
Sprinkle any classic, radioactive, or themed sprinkle to top the cookie slab just before baking.