In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.

In a large bowl, beat the butter until smooth and creamy. Add the sugar and beat until light and fluffy, about 2 minutes. Beat in the egg and vanilla, scraping the sides of the bowl as needed.

Gradually add the flour mixture to the wet ingredients, beating on low until combined.

Divide the dough in half, shape into two disks, and wrap in plastic wrap.

Place dough in the refrigerator to chill until firm, about 1-2 hours.

Preheat the oven to 350 F. Line two baking sheets with parchment paper.

Place one disk of dough between two sheets of parchment paper and roll out to about ¼ inch thickness.

Dip the cookie cutters and stamps into flour. Shake off the excess. Use the cutter to cut out the cookies and the face stamp to imprint Mickey’s and Minnie’s faces onto the cookies. Repeat with second disk of dough.

Place the cookies onto the prepared baking sheets and bake for 8 minutes. Cool on the baking sheet for 5 minutes before transferring the cookies to a wire rack to cool completely.

Once cool, flip half of the cookies over so they’re ready to be filled.

Place the butter in a small saucepan over medium low heat. Melt the butter and let it simmer, stirring with a spatula while it pops and hisses. Continue cooking and stirring until the butter is silent.

Remove the butter from the heat and pour it through a metal strainer into a the bowl of a stand mixer or other large heat-safe bowl.

Add the vanilla, salt, and powdered sugar to the butter. Mix on low speed until the powdered sugar is moist. Then, beat the mixture on medium speed until its creamy and soft, about 5 minutes.

Transfer the filling to a piping bag and immediately pipe it onto the cookies that you previously flipped over.

Gently press the remaining cookies on top of the filling to make a cookie sandwich. Let the cookies set for 30 minutes before serving.