2 cups all-purpose flour
¼ cup whole wheat flour
1 ½ teaspoons fine sea salt
1 ½ teaspoons ground cinnamon
⅛ teaspoon ground nutmeg
1 teaspoon baking powder
1 teaspoon baking soda
2 large eggs, room temperature
1 ¼ cups unsalted butter, room temperature
1 cup granulated sugar
1 cup packed dark brown sugar
1 tablespoon pure vanilla extract
3 cups old-fashioned oats
¼ cup quick-cooking oats
1 ½ cups raisins
Whisk both flours, the salt, cinnamon, nutmeg, baking powder and baking soda in a medium bowl. Whisk the eggs in a small bowl until well-mixed.
Beat the butter and both sugars in a stand mixer fitted with the paddle attachment on medium speed until creamy and very smooth. Scrape the bowl and beat again on medium speed. With the machine running, gradually add the whisked eggs and vanilla and beat until fully incorporated. Scrape the bowl again and beat on low speed. With the machine running, gradually add the flour mixture. Beat until almost incorporated; some streaks of flour should remain. Add both oats and the raisins and beat just until evenly distributed; do not overmix.
Line a rimmed baking sheet with parchment paper. Using a 2-inch-diameter (1 ⅓-ounce) cookie scoop, gently scoop a heaping yet loose mound of dough; you don’t want to pack the dough into the scoop. Gently scrape the hump of the mound against the side of the bowl, then drop the dough onto the baking sheet. Continue scooping the dough, spacing the mounds an inch apart. Using the palm of your hand, gently press all the mounds flat to 2 ½-inch discs. Cover the pan tightly with plastic wrap and refrigerate for at least 3 hours and up to 24 hours.
When ready to bake, heat the oven to 375 degrees. Line two large cookie sheets with parchment paper. Transfer the chilled dough rounds to the prepared sheets, spacing 2 inches apart.
Bake, one sheet at a time, until golden brown around the edges and dry on top, 14 to 16 minutes. Cool on the sheet on a wire rack for 5 minutes, then transfer the cookies to the rack to cool completely. Repeat with the remaining dough.