Swiss Chocolate Sandwich Cookies

This recipe is adapted from that great work Swiss Baking and Confectionery by Walter Bachmann, a Swiss pastry chef who lived in London after the Second World War.

Makes about eighteen sandwich cookies.

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CHOCOLATE COOKIE DOUGH

12 tablespoons (1 1/2 sticks) unsalted butter, softened

4 ounces semisweet chocolate, melted and cooled

1 3/4 cups all-purpose flour (spoon flour into dry-measure cup and level off)

GANACHE FILLING

1/3 cup heavy whipping cream

1 tablespoon unsalted butter

1 tablespoon light corn syrup

2 ounces semisweet chocolate, cut into 1/4-inch pieces

2 ounces milk chocolate, cut into 1/4-inch pieces

Confectioners' sugar for finishing

Two cookie sheets or jelly roll pans lined with parchment or foil

1. To make the dough, beat the butter by hand in a medium bowl just until it is evenly softened. Quickly beat in the melted chocolate, then the flour.  Continuing to mix until dough is smooth.
2. Scrape the dough out onto a piece of plastic wrap and press it into a rectangle about 1/2-inch thick.  Wrap and chill the dough until it is firm – about an hour.
3. While the dough is chilling, make the filling.  Combine the cream, butter and corn syrup in a saucepan and bring to a boil over low heat.  Remove from heat and add both chocolates.  Shake the pan gently to submerge chocolate in the hot liquid.  Let stand 5 minutes, then whisk smooth and scrape filling into a bowl.  Let stand at room temperature or in the refrigerator until of spreading consistency.
4. To bake the cookie bases, set racks in upper and lower thirds of the oven and preheat to 350 degrees.
5. If the dough is very hard, pound it gently with the rolling pin to soften it so that it rolls out more easily.  Divide dough in half and, on a floured surface, roll one half about 3 /16-inch thick.  Use a fluted, round 2-inch cutter to cut the dough into cookies.  Place them on prepared pans as they are cut, leaving about an inch between the cookies.  Repeat with remaining dough.  Save all the scraps.  Re-roll scraps and cut more cookies.
6. Bake the cookies 12 to 15 minutes, until they are firm.  Cool the cookies on the pans on racks.
7. When cookies and filling have cooled, arrange half the cookies, flat side up.  Place a dab of filling on them and cover with the remaining cookies, flat sides together.  Dust cookies very lightly with confectioners' sugar before serving.

COOKIE HINTS

Measuring

1. Unless otherwise instructed by the recipe, spoon flour (cocoa, confectioners’ sugar, cornstarch) into a dry-measure cup and level off. Do not use the measuring cup to scoop up ingredients.
2. Always use large eggs.
3. If you don’t have a scale it’s OK to measure some ingredients visually: if your recipe calls for 5 ounces of chocolate and you have two 4-ounce bars, use 1 1/4 bars.

Mixing

1. If a recipe calls for butter softened to room temperature, then have all the other ingredients at room temperature or adding cold ingredients to the butter will make it firm up again and possibly make the dough or batter separate.
2. Always sift cocoa and confectioners’ sugar before adding to any preparation to avoid lumps. A strainer is okay, you don’t have to use a sifter.
3. For drop cookies that also contain baking powder and/or baking soda, just mix the ingredients until they are smooth.  Over-mixing and incorporating to much air into the dough might make the cookies puff up excessively during baking and fall flat before they are done.

Resting/Chilling/Rolling

1.  Always allow a dough to chill until firm. If the dough is not sufficiently chilled it will be soft and pasty and stick to everything.
2.  Check to see that a chilled dough is firm all the way through before rolling by pressing with a fingertip. If the dough is still soft in the center, the firmer dough on the outside will break into lumps while you are rolling
3.  For soft doughs that have been chilled, cut off a small piece at a time and leave the rest of the dough chilling.   It’s far more efficient to roll several smaller pieces of dough than to roll one large one and have it soften too much to cut out and move the cookies to the pan.
4.  When rolling small pieces of a soft chilled dough, incorporate the scraps right into the next piece of dough rather than re-roll all of them at the end when they might be too soft to roll easily.

Baking

1. Bake in the middle level of the oven unless the recipe specifies otherwise.
2. If you need to bake more than one pan of cookies at a time, use the upper and lower thirds, but switch positions halfway through baking, placing the top an on the lower rack and vice versa, turning the pans front to back at the same time.
3. If you know your over gives very strong bottom heat (cookies burned on the bottom in the past), stack two pans together when baking in the lower third of the oven – this gives a little extra insulation from strong bottom heat.