½ cup (113 grams) unsalted butter, softened¾ cup (165 grams) firmly packed light brown sugar1/3 cup (67 grams) granulated sugar2 large eggs (100 grams), room temperature1 teaspoon vanilla extract1½ cups (150 grams) old-fashioned oats1 cup (125 grams) all-purpose flour2 teaspoons (4 grams) Chai Spice Blend (recipe follows)¾ teaspoon baking soda½ teaspoon kosher salt1 cup (125 grams) finely chopped pecansSpiced Cream Cheese Frosting (recipe follows)
Preheat oven to 350°F (180°C). Line baking sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugars at medium speed until light and fluffy, 2 to 3 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition and stopping to scrape sides of bowl. Beat in vanilla.
In a medium bowl, combine oats, flour, Chai Spice Blend, baking soda, and salt. With mixer on low speed, gradually add oat mixture to butter mixture, beating until nearly combined. Fold in pecans by hand.
Using a 1½-tablespoon spring-loaded scoop, scoop dough (about 30 grams each), and place 3 inches apart on prepared pans.
Bake until edges are just set but centers still seem a little soft, about 15 minutes. Let cool on pans for 5 minutes. Remove from pans, and let cool completely on a wire rack.
Spoon Spiced Cream Cheese Frosting into a pastry bag fitted with a medium open star piping tip (Ateco #826). Pipe buttercream onto flat side of half of cooled cookies. Lightly press remaining cookies, flat side down, on top of buttercream. Refrigerate in an airtight container for up to 5 days.