"3. Stir the sugar into the chocolate mixture, blending until smooth. Stir in the egg and the vanilla. Add the dry ingredients in two additions, mixing only to combine. The dough will be oily."
While the dough may become firm in the fridge, the butter and the chocolate will only withstand so much work before they begin to melt and liquefy again. The rolling action may push them over the edge in terms of work.
Here is one I would like to roll out and cut. Would it work? Thank you.
Hot Chocolate Wafers
½ cup (1 stick) unsalted butter
3 ounces fine-quality bittersweet or semisweet chocolate,such as Lindt Bittersweet, coarsely chopped
½ teaspoon instant espresso powder
1 ¼ cups all-purpose flour, spooned in and leveled
6 tablespoons strained Dutch-processed cocoa powder
1 teaspoon freshly ground black pepper
¼ teaspoon baking soda
1/8 teaspoon salt
3/4 cup superfine sugar
1 large egg, lightly beaten
1 teaspoon pure vanilla extract
1. In a heavy 3-quart saucepan, melt the ·butter over low heat, then add the chocolate. When the chocolate is almost melted, turn off the heat and let the mixture stand, stirring occasionally until the chocolate is completely melted. Blend in the espresso powder. Set aside.
2. Strain together the flour, cocoa powder, black pepper, baking soda, and salt. Set aside.
3. Stir the sugar into the chocolate mixture, blending until smooth. Stir in the egg and the vanilla. Add the dry ingredients in two additions, mixing only to combine. The dough will be oily.
4. Have ready two 12-inch strips of plastic wrap. Shape the dough into two
5 x 1 ¾-inch logs. Wrap each log with plastic, twisting the ends tightly to secure. Refrigerate for 3 hours or until firm. (This dough will keep in the refrigerator for up to 3 days or may be frozen for I month.)
5. position the shelves in the upper and lower thirds of the oven. Heat the oven to 350°.
6. Using a thin, sharp knife, cut the dough into 3/16-inch slices. Bake for 10 or 12 minutes until just set on top.
It seems a little light on the flour to be roll-able, but it could work.
An alternative would be to chill the dough really well and cut it into 1/8 in slices with a cheese slicer. Or roll into small balls, place on parchment, and press down with the bottom of a flat glass dipped in flour.
Dough rolled out to less that 1/8 in can be pretty hard to work with and transfer to the cookie sheet, in my experience.