Mix pistachio paste, almond flour, powdered sugar, salt, and almond extract (optional) into a thick paste. Roll into teaspoon-sized balls and freeze for 30+ minutes.
Whisk flour, cocoa, baking soda, and salt. In another bowl, cream butter and sugars until fluffy. Beat in egg and vanilla, then mix in dry ingredients. Fold in pistachios and chocolate chunks. Chill dough for 30–45 minutes.
Preheat oven to 350°F (175°C). Flatten a heaping tablespoon of dough, place a frozen pistachio ball in the center, and wrap dough around it. Shape into balls and top with extra chocolate or pistachios if desired.
Place on a lined tray, 2 inches apart. Bake for 10–12 minutes until edges are set and tops crack. Cool 5 minutes on tray, then move to a rack.
Enjoy warm with coffee, tea, or milk—gooey centers guaranteed.