Preheat oven to 350 degrees. Place nuts in a single layer on a baking sheet. Place in oven to toast for 7 to 9 minutes. Cool.
Line 2 baking sheets with parchment paper.
In a small saucepan over low heat, melt butter, bittersweet and unsweetened chocolate. Stir occasionally so that chocolate does not burn. Remove from heat and let cool.
Using mixer with a paddle attachment, beat eggs and sugar at medium speed for 3 minutes.
Add vanilla and melted chocolate mixture and beat on medium speed for 2 minutes.
Add flour, baking powder, and salt and stir just until incorporated.
Stir in nuts and chocolate chips.
Let dough rest for 20 minutes.
Use a 1 3/4-inch diameter scoop to drop spoonfuls on prepared sheets, spacing 1 1/2 inches apart.
Wet fingertips with water and gently flatten each cookie.
Bake 10 to 12 minutes, or until the tops begin to crack and look glossy.
Cool 10 minutes and remove to cooling racks.