Cream together the butter and sugar in the bowl of a stand mixer until light and fluffy.
Add in egg, vanilla, and molasses.
Combine the flour, oats, baking soda, salt, cinnamon, and cloves in a separate bowl.
Slowly add the dry ingredients into the wet ingredients. Mix until just combined.
Scoop out the cookie dough onto a lined baking sheet, making sure the cookies are pretty even in size.
Refrigerate the dough for 1 hour, or freeze for 30 minutes.
Preheat the oven to 350 degrees F and bake for 10-14 minutes.
To make the cream filling, beat the butter on medium-high speed for 2 minutes in a large bowl, gradually increasing to high speed.
Add in half of the powdered sugar and mix together.
Add in the heavy cream and vanilla.
Add the rest of the powdered sugar and beat until light and fluffy.
Once the oatmeal cookies have cooled, spread the icing onto one cookie and top with another cookie. Continue with the rest of the cookies.