There a few food items that are truly representative of summer and key lime pie is one of them. However, a true key lime pie would be challenging for a cottage baker. Traditional key lime pie is made with cream cheese and whip cream. Both ingredients that need to be refrigerated. It could be done with flavorings and extracts, but it just wouldn't be the same. I set out to make something that would give you the same experience but in a cookie. And I am a huge fan of portable desserts, a sandwich cookie seemed to be the way to go.
The cookie part is the same as my S'mores Sandwich Cookie. A homemade graham cookie that is firm but still soft and packs a graham flavor that is not found in any store-bought crackers. The filling is a sweet buttercream that is flavored with fresh lime juice, zest, and key lime juice. Then the edges are rolled in graham cracker crumbs.
It took several tries to get the balance of sweet, tart, lime, butter flavor just right in the buttercream. I was hoping to make the filling a bit thicker so it wouldn't ooze out, but you just lost too much of that great lime flavor. Because the filling does still ooze out when you bite into the cookie, I recommend putting the filling that does come out the sides back on top of the cookie. One of my tasters twisted the cookie apart like an Oreo and ate each half separately
which worked really well too. My cookie tasters confirmed that I nailed this one.