In a large bowl, whisk together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
In another bowl, whisk together milk, vanilla, and eggs until frothy. Pour mixture into dry ingredients and whisk to mix. Let rest for about 15 minutes.
To Make the Whiskey Butter Sauce:
In a small saucepan, whisk together butter, sugar, vanilla, and salt over low heat, until butter is melted and sugar has dissolved.
Whisk together half and half and egg in a separate bowl, then pour into butter and sugar mixture in a slow stream, whisking the entire time.
Cook, whisking continuously, for about 5 minutes, until mixture has thickened but is still very pourable.
Remove from heat and whisk in whiskey. Set aside until ready to use.
To Make the Waffles:
Preheat your waffle maker to desired settings. Stir melted butter and chocolate chips into waffle batter until butter is incorporated.
Once the waffle maker is hot, pour approximately 1/3 cup of batter into the wells, close, and cook waffle. Repeat until all batter is used.
Serve waffles with whiskey butter sauce. Top with chopped walnuts, if you like.