1. Preheat oven to 350 degree F and arrange racks in upper and lower thirds. Line 2 cookie sheets with parchment paper.
2. Sift together flour, cocoa, baking soda, and salt in a small bowl.
3. Beat together butter and sugar in a large bowl on high speed until light and fluffy, about 2 minutes. Add egg and extract, beating until combined well.
4. Reduce speed to low and slowly add flour mixture until just combined. Fold in Heath Bites, coffee beans, and walnuts.
5. Using a 1-1/2-inch ice-cream scoop, drop dough onto prepared sheets.
6. Bake, switching cookie sheets halfway through, until set, about 12 minutes. Do not overbake.
7. Transfer cookies on sheets to racks and cool 5 minutes. Transfer cookies to racks and cool completely. (Can be stored at room temperature in an airtight container, in single layers separated by waxed paper, up to 2 weeks.) Makes 24 cookies.