Chocolate Chip Sandwich Cookies

Ingredients:
1 cup walnuts
1 cup plus 2 T all purpose flour
1 teaspoon baking soda
1/2 teaspoon salt
1 stick unsalted butter, at room temperature
1/2 cup packed light brown sugar
1/4 cup granulated sugar
1/2 teaspoon pure vanilla extract
1 large egg
1 cup bittersweet chocolate chips
4 ounces bittersweet chocolate, chopped
5 T heavy cream
2 1/2 T light corn syrup
2 T crème fraîche

Preparing the cookies:
Preheat the oven to 375 degrees F. Spread the nuts in a pie plate and toast for 8 minutes; let cool, then chop.

In a bowl, mix the flour, baking soda and salt. In the bowl of a standing mixer fitted with the paddle (or using a handheld mixer), cream the butter with the sugars and vanilla at medium speed, about 1 minute. Beat in the egg. With the mixer at low speed, beat in the dry ingredients. Beat in the walnuts and chocolate chips. Spoon level tablespoons of the dough onto 2 ungreased baking sheets, about 2 inches apart. Refrigerate for 30 minutes, until firm.

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Preparing the filling:
Put the chocolate in a bowl. In a saucepan, bring the cream and corn syrup to a boil; pour over the chocolate and let stand for 1 minute. Whisk until smooth. Whisk in the crème fraîche. Refrigerate the ganache, stirring occasionally, until thick and spreadable, 1 hour.

Bake the cookies for 12 minutes, until golden; let cool on the sheets for 2 minutes, then transfer to a rack to cool completely.

Sandwich the chocolate chip cookies with the ganache and serve.