Great recipe! I make them all the time. I just do two things differently when I make them as jar mixes: use Domino Brownulated Sugar to avoid having the sugar get hard in the jar, and stick a small crumbled-up piece of wax paper in the top to avoid having the ingredients move around (since the recipe doesn't completely fill the jar.) I cover the top with a small piece of patterned cloth and tie with a ribbon, and you can't see the wax paper.
Prep Time: 20 Minutes
Cook Time: 15 Minutes
Total Time: 35 Minutes, plus at least 30 minutes to chill
1 stick (1/2 cup) unsalted butter
8 oz semi-sweet chocolate, chopped (see note)
3 oz unsweetened chocolate, chopped
3/4 cup all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
3 large eggs
1-1/4 cup sugar
2 teaspoons vanilla extract
12 oz chocolate chips (semi-sweet or milk chocolate both work well)
1-1/4 cups pecans, coarsely chopped
1 heaping cup walnuts, coarsely chopped
Line two baking sheets with parchment paper.
Place the butter in a medium microwave-safe bowl and heat in the microwave until melted, about 1 minute. Add the chopped chocolate and stir to combine. Heat the melted butter and chocolate in the microwave for 20-second intervals, stirring between each bout of heat, until almost melted. Stir, allowing the residual heat in the bowl to melt the chocolate completely. (Alternatively, the butter and chocolate can be melted together slowly in a double boiler on the stovetop.) Set aside and cool to room temperature.