Start the chocolate base In a saucepan over medium heat, melt the butter. Add the cocoa powder (and cinnamon, if using) and stir until fully dissolved.
Add condensed milkPour in the condensed milk and cook, stirring constantly, for about 5–10 minutes until the mixture becomes smooth and slightly thickened.
Check consistencyThe mixture is ready when it starts to pull away from the bottom of the pan and you can see the pan briefly while stirring. Small bubbles may begin to form.
Cool slightlyRemove from heat and let it rest for about 5 minutes.
Add the biscuitsStir in the broken cookies until evenly coated.
Shape and chillSpread the mixture onto a buttered, rimmed baking sheet. Flatten the top with a spatula.
RefrigerateChill for at least 2 hours, or until firm.
Cut and finishCut into squares and roll each piece in granulated sugar or cocoa powder.
Alternative Serving OptionInstead of chilling and cutting, you can transfer the mixture to a glass dish and serve it with a spoon—either warm or chilled.
In Brazil, this recipe is traditionally made with bolacha maisena, a mild, lightly sweet biscuit. If unavailable, Maria cookies are the closest substitute. Any plain tea-style biscuit will also work well. Even lightly flavoured options (like milk & honey biscuits) can be used without affecting the final result.