Make the sugar cookies: In the bowl of a mixer fitted with a paddle attachment, combine butter, sugar, salt, and vanilla extract and beat until light and fluffy. Add egg and beat until well combined. With the mixer still on medium speed, add flour in three parts. Divide dough into two parts and flatten into disks. Wrap each in plastic and refrigerate overnight.
Preheat oven to 350 degrees. Take half the cold dough and roll between two sheets of floured parchment paper until about 3/8" thick, dusting dough with flour as needed. Remove top piece of parchment and cut dough with cookie cutter. Pull away dough scraps from around spoons and set aside. Place parchment paper with cookie spoons on a baking sheet. Freeze for 10 minutes. Roll scraps; cut spoons. Repeat with remaining dough.
Bake until edges are golden brown, 15 to 20 minutes, and let cool on wire racks.
After spoons are cooled completely, dip in desired melted-chocolate mixture.
Make the spicy Mexican dark chocolate spoons: Using a serrated knife, finely chop the dark chocolate and transfer to a glass bowl. Microwave for 30-second intervals until chocolate melts completely. Stir in cinnamon and sugar. Dip spoon in chocolate and let dry on a wire rack. When chocolate is almost dry, sprinkle cayenne pepper on half of the spoon.
Make the mocha-and-milk-chocolate spoons: Melt dark chocolate in microwave in a glass bowl in 30-second intervals. Once melted, stir in instant coffee and sugar. Melt the milk chocolate in the same way. Put 1/4 cup melted mocha chocolate in a small bowl; add 2 tablespoons milk chocolate and swirl the chocolates together with a spoon. Dip cookie spoon in chocolate and let dry on a wire rack.
Make the black-and-white-cookie spoons: Melt bittersweet chocolate in microwave in a glass bowl in 30-second intervals until melted completely. Dip cookie spoon in chocolate and let dry on a wire rack. Meanwhile, melt white chocolate in microwave in a glass bowl in 30-second intervals. Dip cookie spoons in the white chocolate halfway; let dry on wire rack.