Oatmeal Sandwich Cookies with Fluffy Vanilla Buttercream Frosting will make you weak in the knees they’re so good. I’m not kidding! They’re also very rich. So make the cookies tiny – about a tablespoon of dough per cookie – and you’ll end up with cookies that are two or three bites of heaven.
The moment I clicked through to Thalia’s blog post, I knew that I would have to make these cookies. If you haven’t visited Butter and Brioche, you must. Her recipes are creative and utterly reliable. Her recipe was for Oatmeal Sandwich Cookies with Smoked Treacle Buttercream. I’ll be honest, I’d never heard of Treacle, but discovered that it is the British term for molasses. Though her cookies sound perfect as is, I decided to riff on the recipe. I swapped in whole grain flour and stirred in walnuts instead of pecans because I happened to have them on hand. And for the sandwich filling, I went with fluffy vanilla buttercream frosting – my favorite.
When you make these, I recommend that you make them very small, just one or two bites. They are incredibly rich. I love this 1 tablespoon scoop, it’s perfect for scooping cookie dough and frosting for the middle.
This recipe makes about 25 little sandwich cookies. They make a great edible gift, party or holiday treat and they freeze well too!
- 2/3 cup unsalted butter at room temperature
- 1/2 cup granulated sugar
- 3/4 cup brown sugar packed
- 1 egg
- 1 tablespoon vanilla extract
- 1 tsp white vinegar
- ½ tsp salt
- 1 tsp baking powder
- ½ tsp baking soda
- 1 tbsp ground cinnamon
- 1 cup white whole wheat flour 120 g
- 2 ½ cups old-fashioned oats 240 g
- ½ cup chopped walnuts 75 g
- 1 recipe Fluffy Vanilla Buttercream Frosting
- Preheat oven to 350°F.
- Line a baking sheet with parchment paper.
- In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon and salt. Set aside.
- Add butter and sugars to the bowl of a stand mixer fitted with the paddle attachment. Beat at low speed until combined; increase speed and beat until fluffy, 2 to 3 minutes more. Add egg, vanilla and vinegar; beat well, scraping down sides of bowl as needed. Add flour mixture – cover mixer with a kitchen towel to protect your counters from a flour flurry. Start at low speed to stir, then increase to medium and mix until fully combined. Add rolled oats and walnuts; mix just until combined.
- Scoop dough into walnut sized balls (my favorite cookie scoop) and arrange about 2-inches apart on prepared baking sheet. Bake for 8 to 10 minutes, until golden brown on the edges and still soft in the middle. Let rest a few minutes on baking sheet before transferring to a cooling rack. Repeat process with remaining dough.
Once the cookies have cooled, spread your desired amount of fluffy vanilla buttercream frosting on the bottom side of one cookie, and top with another.