A lot of reviewers on AllRecipes said that these taste like Girl Scout Do-si-dos. I haven’t had a Do-si-do in many years, but I can guarantee that (almost) everyone would like this homemade version better. The cookies are softer and the filling is heavenly.
The recipe made exactly 16 sandwich cookies. As with most cookies, it’s better to chill the dough for 30 minutes if you prefer your cookies to be thick rather than flat. I used a small dough scoop to keep the cookies uniform, which worked out really well for this recipe. The dough isn’t sticky, so you don’t have to pick half the dough out of the scooper. 
Peanut Butter & Oatmeal Sandwich Cookies (makes 16 sandwiches)
Ingredients:
For Cookies:
3/4 cup flour
1/2 tsp baking soda
1/4 tsp baking powder
1/2 tsp salt
1/2 cup butter (1 stick), softened
1/2 cup peanut butter
1/2 cup white sugar
1/2 cup packed light brown sugar
1 egg
1 tsp vanilla extract
1 cup oats
For Filling:
3 Tbs butter, softened
1 cup powdered sugar
1/2 cup peanut butter
2 1/2 Tbs heavy cream
In a medium bowl, sift together flour, baking soda, baking powder and salt. Set aside.
In a large bowl cream together butter, sugar, brown sugar and peanut butter. Mix until light and fluffy, at least 2 minutes. Add egg and vanilla and mix until well incorporated. Slowly add dry ingredients. Using a wooden spoon, mix in oats. Chill dough for 30 minutes.
Preheat oven to 350F. Line a baking sheet with parchment paper. Roll approximately a Tbs of dough into a ball. Repeat until the cookie sheet is filled, leaving at least 2 inches between cookies. Use the bottom of a measuring cup to flatten the dough slightly. The cookie should still be about 1/4 inch thick.
Place the remaining dough back in the fridge.
Bake for 8-10 minutes (9 for me) until cookies are slightly golden around the edges. Don’t overbake! Let cookies cool for 5 minutes on a cookie sheet before transferring them to a cooling rack. Repeat the process until all cookies are made and cooled.
To make filling, cream together butter and peanut butter. Slowly add powdered sugar until the filling pulls together. Add 2 1/2 Tbs of cream to thin the filling out a bit. Add more if necessary.
To assemble the cookies place a little less than a Tbs of filling on the back of a cookie. Place another cookie on top (back to back). Store in an airtight container.
Recipe from AllRecipes
