For the Dough
In a medium bowl, whisk together flour, salt and baking powder and set aside.
Using a stand or hand mixer, cream together butter and sugars until light and fluffy, about 2-3 minutes. Add in eggs and vanilla extract, mixing well after each addition.
Combine the cocoa powder with sugars and mix well. Slowly add in the flour mixture, and mix until smooth on low speed.
Shape the dough into two flat discs, wrap in plastic and chill for at least two hours or overnight.
When ready to bake preheat oven to 325º F.
Line baking sheets with parchment paper or non-stick baking sheets and set aside.
One disk at a time, remove the dough from the refrigerator and let it sit for 10-15 minutes. To roll out, sprinkle cocoa powder onto a counter to prevent sticking and roll out dough to ⅛"-¼" inch thick. If the cookie cutter you're using has smaller pieces or angles thicker dough will help. Using a large cookie cutter of your choice, start cutting out the cookies. Using a smaller center cutter, make center cut-outs into half of the cookies.
Transfer cookies onto the prepared cookie sheets and place at least 1-inch apart. Bake for 9 minutes or until the edges are firm and centers are puffed.
Cool on the cookie sheet for 2 minutes and then transfer to a cooling rack. Continue cutting out shapes with the rest of the dough.
Separate the top cookies from the bottom cookies.
When ready to fill, spread about a ½ tablespoon jam or caramel on the inside of the bottom cookie, leaving ⅛ inch around the edges. Place a top cookie on top and carefully press together. Continue with the rest of the top and bottom cookies and the jam/caramel.
Once done "sandwiching" your cookies, top with sifted powdered sugar.