Preheat your oven to 350°F (180°C). Line baking sheets with parchment paper.
In a stand mixer, beat unsalted butter and granulated sugar and light brown sugar at medium speed until fluffy, about 3 to 4 minutes. Scrape down the sides as needed.
Add eggs, one at a time, beating well after each addition. Mix in vanilla extract.
In a separate bowl, sift together all-purpose flour, kosher salt, baking powder, baking soda, ground cinnamon, and apple pie spice.
Gradually add the flour mixture to the butter mixture on low speed until just combined.
Fold in quick-cooking oats, sliced almonds, chopped green and red candied cherries, and chopped dried cherries.
Scoop dough onto prepared baking sheets, placing them 2 inches apart.
Bake for 10 to 15 minutes until edges are golden brown. Let cool for 10 minutes on sheets, then transfer to wire racks to cool completely.
Pipe Cherry Buttercream onto half of the cookies, then top each with another cookie.
Store in an airtight container for up to 4 days.
