Blend the dry ingredients in a mixer fitted with a paddle attachment. Add the butter and mix on low speed until sandy. Add the eggs and mix to combine. Form the dough into a disk, wrap and refrigerate at least 1 hour and up to 3 days. When ready to bake, grease a cookie sheet or line it with parchment paper or a nonstick baking mat. Heat the oven to 375 degrees F.
On a lightly floured surface, roll out the dough to 1/8-inch thickness. Use a cookie cutter to cut out small rounds of dough, 1 to 1 1/2 inches. Transfer to the prepared pan and bake until light golden brown, about 10 minutes. Let cool to room temperature.
Pipe a kiss of marshmallow onto each cookie. Let set at room temperature for 2 hours.
Line a cookie sheet with parchment or a nonstick baking mat. One at a time, gently drop the marshmallow-topped cookies into the hot chocolate. Lift out with a fork and let excess chocolate drip back into the bowl. Place on the prepared pan and let set at room temperature until the coating is firm, about 1 to 2 hours.
Note: if you don't want to make your own marshmallows, you can cut a large marshmallow in half and place on the cookie base. Heat in a preheated 350-degree oven to slump the marshmallow slightly, it will expand and brown a little. Let cool, then proceed with the chocolate dipping.
Homemade Marshmallows: Combine the water, corn syrup, and sugar in a saucepan, bring to a boil until soft-ball stage, or 235 degrees on a candy thermometer. Meanwhile, sprinkle the gelatin over the cold water and let dissolve. Remove the syrup from the heat, add the gelatin, and mix. Whip the whites until soft peaks form and pour the syrup into the whites. Add the vanilla and continue whipping until stiff. Transfer to a pastry bag.
Chocolate Glaze: Melt the 2 ingredients together in the top of a double boiler or a bowl set over barely simmering water.