For the cake:
For the filling:
1. Preheat oven to 360F (180C).
2. Beat soft butter and sugar until light and fluffy, add eggs and vanilla extract, beat until combined.
3. In a separate bowl sift flour, cocoa powder and baking powder. Add salt and stir.
4. Gradually add flour mixture and mix until well combined. Divide the batter into two equal parts and spread into the greased cookie molds (you can buy the molds here: https://bit.ly/36dQGk2)
5. Bake 25-30 minutes. Let cool on a rack until both cookies are chilled.
6. Make the filling: melt the chocolate and set aside to cool. In a large bowl whip heavy cream, powdered sugar and vanilla extract. Whip to stiff peaks. Add melted chocolate, crush in the oreo cookies and gently fold. Refrigerate for 30 minutes.
7. Spread the filling on the first cookie and place the second cookie on top. Refrigerate for at least 4 hours.