✓ Melt butter over low heat until foamy and lightly golden

✓ Add dark and milk chocolate, stir until smooth and glossy

✓ Remove from heat, cool 2 minutes, fold in mini marshmallows

✓ Stir in chopped nuts and dried cranberries until evenly distributed

✓ Add crushed biscuits, mix until the mixture holds together

✓ Press mixture into a parchment-lined 20×20 cm pan, smooth the top

✓ Cool at room temperature 10 minutes then refrigerate 30 minutes

✓ Remove from pan, cut into 24 equal bars with a warm knife

✓ Arrange bars on a platter, optionally dust with cocoa powder

✓ Serve at room temperature, allowing chocolate to soften slightly