1 1/4 cups unsalted butter (2.5 sticks), softened to room temperature
1 cup dark brown sugar
1/2 cup granulated sugar
1 large egg
2 teaspoons vanilla extract
1 tablespoon dark molasses
1 1/2 cups all-purpose flour
1 teaspoon baking soda
1/2 teaspoon salt
3/4 teaspoon ground cinnamon
1/4 teaspoon ground cloves
3 cups uncooked quick-cooking oats (NOT whole-rolled oats)*
3/4 cup (1.5 sticks) unsalted butter, softened to room temperature
3 cups powdered sugar
3 tablespoons heavy cream (using anything with less fat will result in a much less creamy consistency)
1 1/2 teaspoons vanilla extract
pinch of salt, as needed
For the cookies: With a stand or handheld mixer, cream the butter and sugars together at medium speed until light and creamy. Add egg, vanilla, and molasses, scraping down the sides as needed. Set aside.
In a medium-sized bowl, combine the flour, baking soda, salt, cinnamon, and cloves. Whisk it all around. Add the quick oats and combine.
With the mixer running on low, slowly add the dry ingredients to wet ingredients. The dough will be quite thick and you may have to mix it all by hand after a few seconds in the mixer.
Preheat oven to 375F degrees. Line a large cookie sheet with parchment paper or nonstick baking mat. Drop dough with a large cookie scoop, or make sure each ball of dough is 3 tablespoons in measurement. Cookies will spread in the oven, so drop each ball of dough 2 inches apart.
Bake for 10 minutes, until cookies are lightly golden around the edges. Allow cookies to cool on cookie sheet for 3 minutes before transferring to a wire rack to cool completely.
For the filling: With a stand or handheld mixer, beat butter for about 1 minute until creamy. Add the powdered sugar and mix on medium speed for 1-2 minutes. Pour in heavy cream and vanilla extract. Mix on high for 3-4 minutes until fluffy. Taste and add a pinch or two of salt, as needed. If filling is way too thick, add a couple more teaspoons of heavy cream. Spread 1 1/2 tablespoons of cream filling on the bottom side of half of cookies; top with remaining cookies, right side up.
Old-fashioned whole rolled oats will not work in this recipe, but that's usually what I always have on hand. You can make you own quick oats (like I did here) by measuring 3 cups of whole rolled oats and pulsing them in the food processor 4-5 times or until they resemble the consistency of quick oats