In a large mixing bowl, cream together butter and sugar until smooth.

Add eggs one at a time, mixing well and scraping the sides of the bowl.

Mix in vanilla, espresso granules, water, baking powder, and salt.

Gradually add flour (½ cup at a time), mixing until fully combined.

Mix in cocoa powder until the dough is smooth.

Form the dough into a ball, wrap in plastic, and freeze for 30 minutes (not until solid, just firm).

Preheat oven to 375°F (190°C).

Divide chilled dough into two 10-inch logs, spaced at least 2 inches apart on a lined baking sheet.

Bake for 25 minutes. Let cool for 20 minutes.

Slice each log into 12 pieces using a serrated knife.

Place biscotti pieces flat on the baking sheet and toast in the oven for 5–10 minutes on each side.

Melt chocolate chips in a microwave-safe bowl (about 1 minute), stirring until smooth.

Dip each biscotti end into melted chocolate, then into crushed peppermint candy.

Place on wax paper or foil to cool and harden.

Store in an airtight container once completely cooled.