Make the cookies: Whisk the flour, cocoa powder, baking powder and salt in a medium bowl.

Beat the butter, shortening and granulated sugar in a large bowl with a mixer on medium-high speed until light and fluffy, about 2 minutes.

Add the egg, vanilla and food coloring and beat until smooth and the color is fully incorporated.

Reduce the mixer speed to low; add the flour mixture and beat until just combined.

Cover and refrigerate until firm, about 1 hour.

Position racks in the upper and lower thirds of the oven; preheat to 350 degrees F.

Line 2 baking sheets with parchment paper.

Roll tablespoonfuls of dough into balls and arrange 2 inches apart on the prepared baking sheets.

Bake, switching the pans halfway through, until the cookies are puffed and set, 16 to 18 minutes.

Let cool 2 minutes on the baking sheets, then make an indentation in each cookie using the back of a small measuring spoon.

Transfer to racks to cool completely.

Make the filling: Microwave the white chocolate and heavy cream in a microwave-safe bowl in 20-second intervals, stirring, until smooth.

Beat the cream cheese, butter and confectioners' sugar in a bowl with a mixer on medium-high speed until smooth and fluffy, about 2 minutes.

Add the white chocolate mixture, vanilla and salt and beat until smooth.

Transfer to a pastry bag fitted with a star tip and pipe into the indentations in the cookies.

Sprinkle with red sanding sugar.

Store in the refrigerator.