Preheat oven to 400°F and either grease muffin tins or use paper cups or fluted muffin cups.
Using the two bowl method, place the dry ingredients (flour, sugar, baking powder, and salt) in one bowl and mix. Place the liquid ingredients (egg, milk, and oil) in another bowl.
Combine both and stir until lumpy.
Divide the batter evenly and put in five small bowls.
Add the ingredients to make the different flavors of muffins.
Make the brown sugar topping. Add brown sugar, flour, and cinnamon. Cut the cold butter into tiny pieces and using a fork, mix together.
Sprinkle a light amount of topping on top of each muffin.
Place dough in muffin tins and bake 18 - 20 minutes.