3 sheets frozen phyllo dough, thawed
2 tablespoons unsalted butter, melted
2 tablespoons sugar
1 tablespoon cocoa powder, plus more for garnish
1 cup cold heavy cream
2 tablespoons sweetened condensed milk
1/4 teaspoon ground cinnamon
Preheat oven to 325 degrees. Lay 1 sheet phyllo on a work surface, brush phyllo with one-third the butter and sprinkle with one-third the butter. Repeat layer twice more with remaining phyllo, butter, and sugar. Cut stacked phyllo into 6 equal pieces and gently press each square into a cup of a standard muffin pan, crimping edges as needed so phyllo sits flat in bottom of cup.
Bake until phyllo is golden brown, about 20 minutes, rotating pan halfway through. Let cool completely in pan on a wire rack.
Meanwhile, in a medium bowl, combine cocoa powder, cream, condensed milk, cinnamon, and a pinch of salt. Whisk until firm but not dry peaks form. Refrigerate until ready to serve. Fill phyllo cups with cream and sprinkle with cocoa powder. Serve immediately.