With a layer of delicious melted milk chocolate between two layers of soft, perfectly tender vanilla spiced cookies, these cookie sandwiches will be a hit!
In a medium bowl, sift together flour, cornstarch, baking powder, baking soda, salt, and spices: cinnamon, ginger, nutmeg, allspice, cloves, orange zest. Set aside.
In a mixer bowl fitted with the paddle attachment, beat butter and sugar on medium speed until light and fluffy, about 3 minutes. Beat in egg & yolks, molasses, and vanilla extract just until combined. Reduce speed to low. Add the flour mixture and beat just until combined. Do not overmix or the cookies will turn out tough. When making the dough, if it feels dry, you can add a little bit of cold water or milk a little at a time, just until the dough comes together.
Form the dough into a ball, then flatten slightly to form a disc. Chill the dough for about 15 minutes to roll it out right away and start cutting cookies (easiest). If you don’t want to use the dough right away, you can refrigerate it for up to 3 days or freeze it for up to a month, then thaw it overnight in the fridge. Take the dough out of the fridge and let it sit on the counter for a few minutes to soften slightly for easy rolling.
On a lightly floured surface, roll the dough to a ⅛ or ¼-inch (3-5mm) thickness. Cut out into rounds using a 2-inch (5cm) fluted or round cookie cutter, and place the cookies on baking sheets lined with parchment paper. If at any point the dough becomes too warm, place it back into the fridge for a few minutes. Re-roll the remaining scraps and repeat.
Alternatively, roll into 1-inch sized round balls, place them on a parchment lined pan, and use a floured cookie stamp to press the cookies flat into a design.
Place sheets with cookies in the fridge for about 30 minutes, until firm, so that they will be less prone to spreading.
Preheat oven to 350F/180C. Bake for 6-8 minutes for small cookies or up to 10 minutes for larger cookies, or until cookies appear golden brown at the edges. Allow cookies to cool in the pan for 10 minutes, then gently transfer to a wire rack to cool completely.
Melt the milk chocolate chips in the microwave using the instructions on the bag. Chocolate should no longer have lumps and be easily spreadable. Spread the bottom half of the cookies with about a teaspoon of melted chocolate. Sandwich together with remaining cookies, pressing slightly so that the chocolate oozes out to the sides.