Make the cookies: In a small saucepan, bring the champagne to a boil and reduce by half, about 5 minutes.
2. Step
In a liquid measuring cup or microwave-safe bowl, microwave the heavy cream until boiling.
3. Step
Pour the hot heavy cream and half of the heated champagne over the white chocolate chips in a heatproof bowl and let rest for 1 minute. Whisk until smooth. Add 4 tbsp of unsalted butter and whisk until melted and well combined. Cover and chill in the refrigerator for 2 hours.
4. Step
In a large bowl, cream the remaining cup of unsalted butter and the powdered sugar with an electric hand mixer until fluffy. Add the vanilla and beat to combine.
5. Step
Add the flour, 1 cup at a time, and beat until just incorporated. To the last addition, add the salt.
6. Step
Add the walnuts and beat to incorporate. Using your hands, press the dough together in a ball and wrap in plastic wrap. Refrigerate the dough at least 30 minutes.
7. Step
Preheat the oven to 375˚F (190˚C). Line a baking sheet with parchment paper.
8. Step
Use a 2 tablespoon (1 ounce) scoop to scoop balls of cookie dough onto the prepared baking sheet. Pat each ball into a disc in your palm and fill with 1 teaspoon of the white chocolate ganache. Fold the edges in to completely cover the ganache and roll back into a ball. Once all of the cookies are filled, refrigerate for 15 minutes.
9. Step
Bake the cookies for 15 minutes, until set and not too browned. Let cool.
10. Step
Make the glaze: Microwave the heavy cream until boiling.
11. Step
Pour the hot heavy cream and the remaining reduced champagne over the semisweet chocolate chips in a heatproof bowl and whisk until smooth.
12. Step
Dip the cooled cookies in the chocolate ganache and sprinkle with edible gold dust.
