Source: Cook's Illustrated's The New Best Recipe
1 1/2 cups all-purpose flour
1/2 tsp salt
1/2 tsp baking powder
1/4 tsp freshly grated nutmeg
1 cup unsalted butter, softened
1 cup light brown sugar, packed
1 cup granulated sugar
2 large eggs
3 cups rolled oats
1 1/2 cups raisins
1. Adjust the oven racks to the low and middle positions and heat the oven to 350º. Line 2 large baking sheets and heat the oven to 350º. Line 2 large baking sheets with parchment paper or spray them with nonstick cooking spray.
2. Whisk the flour, baking powder, nutmeg and salt together in a medium bowl.
3. Either by hand or with an electric mixer, beat the butter on medium speed until creamy. Add the sugars; beat until fluffy, about 3 minutes. Beat in the eggs, one at a time.
4. Stir the dry ingredients into the butter-sugar mixture with a wooden spoon or large rubber spatula. Stir in the oats and raisins.
5. Working with a generous 2 tablespoons of dough each time, roll the dough into 2-inch balls. Place the balls on the prepared baking sheets, spacing them at least 2 inches apart.
6. Bake until the cookies edges turn golden brown, 22-25 minutes, rotating baking sheets front to back and top to bottom halfway through the baking time. Let the cookies cool on the baking sheets for 2 minutes. Transfer the cookies with a wide metal spatula to a wire rack. Let cool at least 30 minutes.
My notes: I love the texture of these cookies - very chewy and hearty. I sometimes add nuts as well.
See Orange and Almond Oatmeal Cookies for a more tasty variation on this oatmeal cookie.