Preheat oven to 375°F (190ºC). Grease 24 mini muffin cups. Set aside.
Reserve 1 tbsp (15 mL) of flour. In large bowl, whisk remaining flour with sugar, baking powder and salt. Set aside. Reserve 1 tbsp (15 mL) of milk. In second bowl, whisk remaining milk with egg, 1/3 cup (75 mL) melted butter and vanilla.
Stir wet ingredients into dry ingredients just until moistened. Divide half the batter among 24 mini muffin cups. In bowl, mix brown sugar, reserved 1 tbsp (15 mL) flour, remaining butter and cinnamon. Dollop 1/2 tsp (2 mL) of this brown sugar streusel onto batter in each muffin cup; top with remaining muffin batter. Using a toothpick, swirl batter in each cup to resemble pattern on cinnamon buns.
Bake 15 min. until muffins are golden brown and tops spring back when lightly pressed. Cool muffin pan on rack.
Meanwhile, make icing by beating together cream cheese, icing sugar, reserved 1 tbsp (15 mL) milk and orange zest. Remove muffins from pan. Drizzle with icing. Serve warm or at room temperature.
Add finely chopped pecans or raisins to brown sugar streusel.