An egg-free, alcohol-free chilled chocolate-biscuit log, cut into sixteen small slices.

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Toast 3/4 cup chopped walnuts briefly in a dry pan until fragrant and let cool. Break plain tea biscuits into two measured cups of small pieces, not fine crumbs. Line a work surface with a large sheet of parchment.
Melt 8 oz chopped semisweet chocolate with 1/4 cup butter gently in a heatproof bowl over barely simmering water, keeping steam out of the bowl. Warm 1/4 cup whole milk separately and stir gradually into the smooth chocolate, followed by 1 tbsp cocoa powder.
Fold in biscuit pieces and cooled walnuts until evenly coated. Spoon onto the parchment and shape into one compact log about 2 inches in diameter, twisting and sealing the paper ends. Chill at least four hours until firm enough to slice.
Unwrap, dust lightly with 2 tbsp confectioners' sugar and cut approximately sixteen small slices with a sharp knife. Keep chilled until serving. Record binding, sliced pattern, firm set and actual yield in a kitchen trial; no raw egg or alcohol is used.

Recipe-development draft; not kitchen-tested. Timing and yield are estimates. Nutrition has not been calculated.

Additional chilling, resting or cooling time: 240 minutes, included in the total.

Untested estimate: chocolate melting/toasting about ten minutes and at least four-hour refrigerated set; actual slice texture and yield need trial.