In medium saucepan, combine water, butter, 3 tablespoons sugar and salt. Heat over medium heat until mixture comes to a boil. Reduce heat to medium low and add flour. Mix with a wooden spoon until mixture forms a ball. Continue cooking mixture, stirring constantly, for 5 minutes. Remove to a large bowl and cool slightly. Add eggs, 1 at a time; stirring until completely incorporated and dough is smooth. Set aside.
In medium bowl, combine remaining 1/2 cup sugar, cardamom and cinnamon.
In medium bowl, combine chocolates. Pour steaming half and half over chocolate; let stand 5 minutes. Add chili powder, cayenne and salt. Stir until smooth.
In heavy bottom 2 quart saucepan, heat vegetable oil to 375° F using a candy thermometer.
Place dough in 16 in. decorating bag fitted with decorating tip 1B. Pipe dough in 2-3 in. pieces; snip with scissors into hot oil. Fry until churros are golden brown on all sides, about 2-3 minutes. Cook no more than 4 churros at a time. Once browned, remove churros to paper towel-lined jelly roll pan. Cool slightly. Toss churros in cardamom sugar and serve with warmed hot chocolate.