Preheat the oven to 400 degrees F. Prepare baking sheets with parchment paper. Put the butter in the microwave for 8 seconds to slightly soften it. With the handheld mixer, beat the butter and brown sugar together until fluffy. Add the eggs, milk, vanilla, and salt. Scrape down the sides with a spatula, and mix until fully combined.
1 cup butter, 1 1/2 cups packed light brown sugar, 1/2 cup milk, 2 eggs, 1/2 teaspoon vanilla extract, 1 teaspoon salt
Add the flour, cinnamon, nutmeg, baking soda, and baking powder. Mix until just combined. Don't overmix. Scrape down the sides with a spatula, then add the oats, chopped pecans, and raisins. Mix with the handheld mixer until fully combined. Make sure there's no dry oats at the bottom.
1 3/4 cups all-purpose flour, 1 teaspoon cinnamon, 1/2 teaspoon nutmeg, 1/4 teaspoon baking soda, 3 cups oats, 3/4 cups chopped pecans, 1/4 cup raisins, 2 teaspoons baking powder
Use a cookie scoop to scoop 8 dollops of cookie dough onto each baking sheet. The dollops should be about 2-3 tablespoons each. Dip a spoon in water and use the back to slightly press down each cookie. Wipe up any excess water on the cookies with a paper towel. Bake the cookies in the preheated oven for 8 minutes. When they're done, they should be golden brown with a browned bottom. Let them cool completely for 5 minutes, and store in an airtight container at room temperature for up to a week. Enjoy!