• Plan ahead. These skull cookies take about 1 to 2 days to make because the dough needs to be chilled twice.
• Make cookie dough. In a medium bowl, combine 1 cup butter, ½ cup + 2 tablespoon confectioners' sugar, and 1 teaspoon vanilla. Using an electric mixer, beat until the mixture is creamy and smooth, about 2 minutes. Add 2 ½ cups flour and ¼ teaspoon salt and beat to combine.
• Roll the dough. Divide the dough in half and shape each portion into a disc. Roll each disc between two sheets of parchment paper until about ⅛ to ¼ inch thick.

  Keeping the dough between the parchment sheets, transfer it to the refrigerator and chill for at least 4 hours, or up to a day.
• Cut skull shapes. Use a skull cookie cutter to cut shapes from the chilled dough.

  👉 For half of the cookies (the top layer of the sandwich skulls), cut out the eyes and mouth.
  
• Eyes. Use a round piping tip to punch out two holes.

  Mouth. Gently press one side of a round fluted cookie cutter into the lower part of the face, being careful not to cut all the way through.
  
• Chill again. Place all the cut cookies on parchment-lined baking sheets, spacing them about an inch apart, and chill for at least an hour or up to a day.
• Bake. Preheat the oven to 350°F (177°C). Bake cookies one sheet pan at a time for 20 to 24 minutes, or until golden in color. Let cool completely.
  

Make M&M flowers

• Cut candy. Using a sharp knife, carefully cut each M&M in half.
  
• Make flowers. Place a small dollop of melted chocolate on parchment paper. Arrange the halved M&Ms in a circle, with the cut sides facing down to create a flower shape. Transfer the parchment paper to the refrigerator and chill until the chocolate is completely set.

  👉 For a more uniform look, I like to use the same M&M color for each flower.
  

Finish cookies

• Fill with jam. Spread a thin layer of raspberry jam on a whole cookie. Gently press a cut-out cookie on top, aligning the edges to form a sandwich.
  
• Decorate. Place a small dollop of melted chocolate on one side of the cookie face. Gently press an M&M flower into the chocolate, ensuring it's centered. Allow the chocolate to set completely before serving, for at least one hour.