Oatmeal Raisin Skillet Cookie

Preheat the oven to 350u0b0F.
Spray an 8-inch cast-iron skillet with nonstick cooking spray.
Place the softened butter, brown sugar, granulated sugar, and vanilla extract into a large bowl. Use a mixer to cream together the butter and sugars on medium speed for 1 minute, or until pale and fluffy. Add the egg and continue to beat on medium speed for 30 seconds to one minute, until light and fluffy.
Add the flour, oats, cinnamon, nutmeg, baking soda, and salt to the bowl. Beat the mixture on medium speed for about 1 minute, until all ingredients are combined. Scrape down the sides of the bowl with a rubber spatula, as needed.
Fold the raisins and chopped walnuts into the cookie dough until they are evenly distributed.
Transfer the cookie dough into the cast-iron skillet. Use a spoon or clean hands to press the dough into an even layer.
Bake the cookie for 28-30 minutes on the middle rack of oven, until golden-brown at the edges and a toothpick inserted in the center comes out clean.
Check to see that the cookie is done. Remove from oven or add time as needed.
Allow the cookie to cool for 10 minutes before serving.
Serve the cookie warm directly from the skillet. Alternatively, the cookie may be cooled to room temperature in the skillet, then cut into slices.