Step 1: Make the Oatmeal Cookie Dough

1. Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. In a large mixing bowl, cream together the butter, brown sugar, and granulated sugar until light and fluffy.
3. Add the eggs, molasses, and vanilla extract, mixing until well combined.
4. In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon.
5. Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
6. Fold in the oats until evenly distributed.

Step 2: Bake the Cookies

1. Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them 2 inches apart.
2. Bake for 10-12 minutes, or until the edges are lightly golden brown.
3. Allow the cookies to cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.

Step 3: Prepare the Cream Filling

1. In a mixing bowl, beat the butter until smooth.
2. Gradually add the powdered sugar, beating until light and fluffy.
3. Mix in the vanilla extract and heavy cream until the filling reaches a creamy consistency.

Step 4: Assemble the Oatmeal Cream Pies

1. Spread or pipe a generous amount of filling onto the flat side of one cookie.
2. Place another cookie on top and gently press to form a sandwich.
3. Repeat with the remaining cookies.