Preheat oven to 375 degrees F. Grease 24 to 32 mini muffin cups or line with paper liners. I use muffin cups that hold 3 ½ tablespoons.
Mix the flour, baking powder, baking soda and salt together in a bowl and set aside.
In a mixing bowl beat the butter and both both sugars until creamy. Beat in the egg and vanilla, scraping sides of the bowl. By hand, stir the flour mixture and yogurt into the batter alternating between the two and being careful not to overmix. Stir in the chocolate or butterscotch chips.
Using about a tablespoon, fill the muffin cups just to the top. They will rise and spread a bit, so you don’t want to pile the batter too high. If you get 32 minis, you’ve used the right amount per cup. Sprinkle cinnamon sugar over top of each muffin. Sprinkle with some cinnamon sugar if you like.
Bake for 18 minutes or until muffins are golden brown and cooked through.